diff --git "a/frontend/src/App.css" "b/frontend/src/App.css"
new file mode 100644--- /dev/null
+++ "b/frontend/src/App.css"
@@ -0,0 +1,4333 @@
+/* ========================================
+   App Layout
+   ======================================== */
+
+/* ========================================
+   Premium Header
+   ======================================== */
+.premium-header {
+    height: 60px;
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    padding: 0 1.5rem;
+    background: rgba(var(--bg-canvas-rgb, 255, 255, 255), 0.75);
+    backdrop-filter: blur(20px);
+    -webkit-backdrop-filter: blur(20px);
+    border-bottom: 1px solid var(--border-light);
+    position: sticky;
+    top: 0;
+    z-index: 1000;
+    transition: transform 0.3s ease, opacity 0.3s ease, box-shadow 0.3s ease;
+    /* Exclude color/background from transition to prevent flickering on theme switch */
+}
+
+.dark .premium-header {
+    background: rgba(9, 9, 11, 0.75);
+    /* Zinc 950 */
+    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
+}
+
+.header-left {
+    display: flex;
+    align-items: center;
+    gap: 1rem;
+}
+
+.brand-wrapper {
+    display: flex;
+    align-items: center;
+    gap: 0.25rem;
+    cursor: pointer;
+    padding: 0.5rem 0.75rem;
+    border-radius: 0.75rem;
+    transition: background 0.2s;
+}
+
+.brand-wrapper:hover {
+    background: var(--bg-surface-hover);
+}
+
+.brand-name {
+    font-family: 'Outfit', sans-serif;
+    font-size: 1.15rem;
+    font-weight: 700;
+    letter-spacing: -0.02em;
+    color: var(--text-primary);
+}
+
+.brand-version {
+    color: var(--text-tertiary);
+    font-weight: 500;
+    font-size: 0.95rem;
+    margin-left: 2px;
+}
+
+.brand-dropdown-icon {
+    color: var(--text-tertiary);
+}
+
+.header-center {
+    position: absolute;
+    left: 50%;
+    transform: translateX(-50%);
+}
+
+.upgrade-pill {
+    /* Layout & Spacing */
+    display: flex;
+    align-items: center;
+    gap: 0.6rem;
+    padding: 0.5rem 1.125rem;
+    border-radius: 9999px;
+
+    /* Typography - Bold for impact */
+    font-size: 0.85rem;
+    font-weight: 700;
+    letter-spacing: 0.01em;
+
+    /* Aesthetics (Bold & Sharper) */
+    background: linear-gradient(135deg,
+            rgba(var(--brand-primary-rgb), 0.20) 0%,
+            rgba(var(--brand-primary-rgb), 0.10) 100%);
+    color: var(--brand-primary);
+    border: 1px solid rgba(var(--brand-primary-rgb), 0.45);
+
+    /* Deeper shadow for 3D feel */
+    box-shadow: 0 4px 12px rgba(var(--brand-primary-rgb), 0.12);
+
+    /* Rendering & smoothness */
+    cursor: pointer;
+    position: relative;
+    overflow: hidden;
+    transition: all 0.4s cubic-bezier(0.2, 0.8, 0.2, 1);
+    transform: translateZ(0);
+    /* Hardware accel only, no movement */
+    backdrop-filter: blur(8px);
+    -webkit-backdrop-filter: blur(8px);
+}
+
+/* Dark mode adjustment (Kept subtle) */
+.dark .upgrade-pill {
+    background: linear-gradient(135deg,
+            rgba(var(--brand-primary-rgb), 0.15) 0%,
+            rgba(var(--brand-primary-rgb), 0.05) 100%);
+    border-color: rgba(var(--brand-primary-rgb), 0.3);
+    color: rgb(165, 180, 252);
+    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
+}
+
+/* Hover State - Even Bolder */
+.upgrade-pill:hover {
+    background: linear-gradient(135deg,
+            rgba(var(--brand-primary-rgb), 0.30) 0%,
+            rgba(var(--brand-primary-rgb), 0.20) 100%);
+    border-color: rgba(var(--brand-primary-rgb), 0.7);
+    box-shadow:
+        0 6px 16px rgba(var(--brand-primary-rgb), 0.25),
+        0 0 0 1px rgba(var(--brand-primary-rgb), 0.15);
+    /* Pronounced glow */
+    transform: translateZ(0);
+    /* Still no movement */
+    color: var(--brand-hover);
+}
+
+.dark .upgrade-pill:hover {
+    background: linear-gradient(135deg,
+            rgba(var(--brand-primary-rgb), 0.25) 0%,
+            rgba(var(--brand-primary-rgb), 0.1) 100%);
+    box-shadow:
+        0 4px 20px rgba(0, 0, 0, 0.3),
+        0 0 15px rgba(var(--brand-primary-rgb), 0.15);
+}
+
+.upgrade-pill:active {
+    transform: scale(0.97);
+}
+
+.sparkle-icon {
+    animation: rotateSparkle 2s infinite linear;
+}
+
+@keyframes rotateSparkle {
+    0% {
+        transform: scale(1) rotate(0);
+    }
+
+    50% {
+        transform: scale(1.2) rotate(180deg);
+        opacity: 0.8;
+    }
+
+    100% {
+        transform: scale(1) rotate(360deg);
+    }
+}
+
+.header-right {
+    display: flex;
+    align-items: center;
+    gap: 0.75rem;
+}
+
+.header-menu-container {
+    position: relative;
+    display: flex;
+    align-items: center;
+}
+
+.header-dropdown {
+    top: calc(100% + 0.5rem) !important;
+    right: 0 !important;
+    transform-origin: top right;
+}
+
+.header-icon-btn,
+.header-action-btn {
+    background: transparent;
+    border: none;
+    color: var(--text-secondary);
+    cursor: pointer;
+    border-radius: 0.5rem;
+    transition: transform 0.2s, opacity 0.2s, box-shadow 0.2s;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    outline: none !important;
+}
+
+.header-icon-btn {
+    width: 2.5rem;
+    height: 2.5rem;
+}
+
+.header-action-btn {
+    padding: 0.5rem 0.75rem;
+    gap: 0.5rem;
+    font-size: 0.85rem;
+    font-weight: 500;
+}
+
+.header-icon-btn:hover,
+.header-action-btn:hover {
+    background: var(--bg-surface-hover);
+    color: var(--text-primary);
+}
+
+.help-btn {
+    font-family: 'Outfit', sans-serif !important;
+    font-weight: 600 !important;
+    height: 2.5rem !important;
+    /* Match 40px height of other header buttons */
+    padding: 0 1rem !important;
+    display: flex !important;
+    align-items: center !important;
+    justify-content: center !important;
+    gap: 0.5rem !important;
+    line-height: 1 !important;
+}
+
+.help-btn .btn-label {
+    margin: 0 !important;
+    display: inline-block !important;
+    line-height: normal !important;
+}
+
+.user-avatar-container {
+    position: relative;
+    display: flex;
+    align-items: center;
+}
+
+.user-avatar-wrapper {
+    width: 2.5rem;
+    height: 2.5rem;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    cursor: pointer;
+    border-radius: 50%;
+    transition: transform 0.2s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.2s cubic-bezier(0.4, 0, 0.2, 1);
+    /* Exclude background/color from transition to prevent flickering on theme switch */
+}
+
+.user-avatar-wrapper:hover,
+.user-avatar-wrapper.active {
+    background: var(--bg-surface-hover);
+}
+
+.user-avatar img {
+    width: 100%;
+    height: 100%;
+    object-fit: cover;
+}
+
+.user-avatar {
+    width: 2.2rem;
+    height: 2.2rem;
+    background: var(--bg-surface);
+    border-radius: 50%;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    overflow: hidden;
+    color: var(--text-secondary);
+    border: 1px solid var(--border-light);
+    transition: transform 0.2s, opacity 0.2s;
+    /* Exclude border/background/color from transition to prevent flickering on theme switch */
+}
+
+.user-avatar-wrapper:hover .user-avatar {
+    border-color: var(--brand-primary);
+    color: var(--brand-primary);
+}
+
+.user-dropdown {
+    top: calc(100% + 0.5rem) !important;
+    right: 0 !important;
+    min-width: 220px !important;
+    transform-origin: top right;
+}
+
+.user-dropdown-header {
+    padding: 1rem 1.25rem;
+}
+
+.user-info {
+    display: flex;
+    flex-direction: column;
+}
+
+.user-name {
+    font-size: 0.95rem;
+    font-weight: 700;
+    color: var(--text-primary);
+}
+
+.user-email {
+    font-size: 0.8rem;
+    color: var(--text-tertiary);
+    margin-top: 2px;
+}
+
+/* Mobile Specific Header Adjustments */
+@media (max-width: 768px) {
+    .premium-header {
+        padding: 0 1rem;
+        height: 56px;
+    }
+
+    .btn-label {
+        display: none;
+    }
+
+    .upgrade-pill {
+        display: none;
+        /* Hide upgrade on mobile center to save space */
+    }
+
+    .header-center {
+        display: none;
+    }
+
+    .brand-name {
+        font-size: 1rem;
+    }
+}
+
+.app-container {
+    display: flex;
+    height: 100vh;
+    height: 100dvh;
+    overflow: hidden;
+    background: var(--bg-canvas);
+    color: var(--text-primary);
+}
+
+/* ========================================
+   Sidebar
+   ======================================== */
+.sidebar {
+    width: 280px;
+    background: var(--bg-surface);
+    border-right: 1px solid var(--border-light);
+    display: flex;
+    flex-direction: column;
+    transition: width 0.3s cubic-bezier(0.16, 1, 0.3, 1);
+    flex-shrink: 0;
+    overflow: hidden;
+}
+
+.sidebar.collapsed {
+    width: 70px;
+}
+
+.sidebar-header {
+    padding: 1rem;
+    display: flex;
+    align-items: center;
+    gap: 0.75rem;
+    border-bottom: 1px solid transparent;
+}
+
+.history-label.collapsible {
+    cursor: pointer;
+    user-select: none;
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    padding: 0 1.5rem 0.5rem;
+    font-size: 0.8rem;
+    font-weight: 600;
+    color: var(--text-tertiary);
+    transition: color 0.2s ease;
+}
+
+.history-label.collapsible:hover {
+    color: var(--text-primary);
+}
+
+.history-label.collapsible svg {
+    opacity: 0.5;
+    transition: transform 0.2s ease;
+}
+
+/* Sidebar Chat Item Refinements */
+.sidebar-chat-item {
+    position: relative;
+    padding: 8px 12px 8px 14px;
+    /* Tighter padding as requested */
+    font-size: 14.2px;
+    /* Slightly larger for readability */
+    font-weight: 500;
+    color: var(--text-secondary);
+    display: flex;
+    align-items: center;
+    border-radius: 8px;
+    cursor: pointer;
+    transition: opacity 0.35s cubic-bezier(0.4, 0, 0.2, 1);
+    z-index: 1;
+    /* Base priority */
+}
+
+.sidebar-chat-item.menu-open {
+    z-index: 100;
+    /* Priority elevation when menu is open */
+}
+
+.active-indicator {
+    position: absolute;
+    left: 0;
+    top: 50%;
+    transform: translateY(-50%) scaleY(0.7);
+    /* Subtle pop entry */
+    width: 3px;
+    height: 18px;
+    background: #3b82f6;
+    border-radius: 0 4px 4px 0;
+    opacity: 0;
+    transition: opacity 0.3s cubic-bezier(0.34, 1.56, 0.64, 1),
+        transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
+    z-index: 5;
+}
+
+.sidebar-chat-item.active .active-indicator {
+    opacity: 1;
+    transform: translateY(-50%) scaleY(1);
+}
+
+.sidebar-chat-item.active {
+    background: rgba(59, 130, 246, 0.08);
+    color: var(--text-primary);
+    font-weight: 600;
+}
+
+.dark .sidebar-chat-item.active {
+    background: rgba(59, 130, 246, 0.15);
+}
+
+.sidebar-chat-item:hover:not(.active) {
+    background: var(--bg-surface-hover);
+    color: var(--text-primary);
+}
+
+.chat-item-text {
+    flex: 1;
+    overflow: hidden;
+    white-space: nowrap;
+    text-overflow: clip;
+    margin-right: 28px;
+    /* More space between text and actions */
+}
+
+.chat-item-text.editing {
+    margin-right: 0;
+    padding-right: 0;
+    display: flex;
+    align-items: center;
+    width: 100%;
+}
+
+.inline-rename-input {
+    width: 100%;
+    background: transparent;
+    border: none;
+    border-bottom: 1px solid #3b82f6;
+    padding: 0;
+    margin: 0;
+    font-size: 14.2px;
+    font-family: inherit;
+    font-weight: inherit;
+    color: var(--text-primary);
+    outline: none;
+    line-height: inherit;
+}
+
+.dark .inline-rename-input {
+    border-bottom-color: #3b82f6;
+}
+
+.chat-item-actions {
+    position: absolute;
+    right: 8px;
+    display: flex;
+    align-items: center;
+    opacity: 0;
+    transform: translateX(4px);
+    /* Slide effect */
+    transition: opacity 0.25s cubic-bezier(0.4, 0, 0.2, 1),
+        transform 0.25s cubic-bezier(0.4, 0, 0.2, 1);
+    z-index: 10;
+}
+
+.sidebar-chat-item:hover .chat-item-actions,
+.sidebar-chat-item.active .chat-item-actions,
+.chat-item-actions:has(.chat-menu-dropdown) {
+    opacity: 1;
+    transform: translateX(0);
+}
+
+.menu-trigger-btn {
+    background: none;
+    border: none;
+    padding: 2px;
+    color: var(--text-tertiary);
+    cursor: pointer;
+    border-radius: 4px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    transition: color 0.2s ease, background 0.2s ease;
+}
+
+.menu-trigger-btn:hover {
+    color: var(--text-primary);
+    background: rgba(0, 0, 0, 0.04);
+}
+
+.dark .menu-trigger-btn:hover {
+    background: rgba(255, 255, 255, 0.08);
+}
+
+.chat-menu-dropdown {
+    position: absolute;
+    top: 100%;
+    right: 0;
+    z-index: 1000;
+    width: 170px;
+    /* Slightly wider for better spacing */
+    background: #ffffff;
+    border: 1px solid rgba(0, 0, 0, 0.08);
+    border-radius: 12px;
+    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
+    padding: 6px;
+    margin-top: 6px;
+    transform-origin: top right;
+    animation: menuSmoothEntry 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
+}
+
+.chat-menu-dropdown.placement-top {
+    top: auto;
+    bottom: 100%;
+    margin-top: 0;
+    margin-bottom: 6px;
+    transform-origin: bottom right;
+    animation: menuSmoothEntryUp 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
+}
+
+@keyframes menuSmoothEntry {
+    from {
+        opacity: 0;
+        transform: scale(0.9) translateY(-6px);
+    }
+
+    to {
+        opacity: 1;
+        transform: scale(1) translateY(0);
+    }
+}
+
+@keyframes menuSmoothEntryUp {
+    from {
+        opacity: 0;
+        transform: scale(0.9) translateY(6px);
+    }
+
+    to {
+        opacity: 1;
+        transform: scale(1) translateY(0);
+    }
+}
+
+.dark .chat-menu-dropdown {
+    background: #2d2d2d;
+    border-color: rgba(255, 255, 255, 0.1);
+    box-shadow: 0 4px 25px rgba(0, 0, 0, 0.5);
+}
+
+.menu-item {
+    width: 100%;
+    display: flex;
+    align-items: center;
+    gap: 12px;
+    padding: 8px 10px;
+    border: none;
+    background: none;
+    color: #4b5563;
+    font-size: 14.2px;
+    font-weight: 500;
+    border-radius: 6px;
+    cursor: pointer;
+    transition: background 0.15s ease;
+}
+
+.dark .menu-item {
+    color: #d1d5db;
+}
+
+.menu-item:hover {
+    background: #f3f4f6;
+}
+
+.dark .menu-item:hover {
+    background: rgba(255, 255, 255, 0.05);
+}
+
+.menu-item.delete {
+    color: #ef4444;
+}
+
+.menu-item.delete:hover {
+    background: rgba(239, 68, 68, 0.05);
+}
+
+.menu-separator {
+    height: 1px;
+    background: #f3f4f6;
+    margin: 4px 0;
+}
+
+.dark .menu-separator {
+    background: rgba(255, 255, 255, 0.05);
+}
+
+@keyframes menuFadeIn {
+    from {
+        opacity: 0;
+        transform: translateY(-4px);
+    }
+
+    to {
+        opacity: 1;
+        transform: translateY(0);
+    }
+}
+
+.dark .chat-menu-dropdown {
+    background: var(--bg-sidebar-dropdown, rgba(35, 35, 35, 0.95));
+    border-color: rgba(255, 255, 255, 0.08);
+}
+
+.menu-item {
+    width: 100%;
+    display: flex;
+    align-items: center;
+    gap: 12px;
+    padding: 8px 12px;
+    border: none;
+    background: none;
+    color: var(--text-secondary);
+    font-size: 13.5px;
+    font-weight: 500;
+    border-radius: 8px;
+    cursor: pointer;
+    transition: transform 0.15s ease, opacity 0.15s ease;
+}
+
+.menu-item:hover {
+    background: var(--bg-surface-hover);
+    color: var(--text-primary);
+}
+
+.menu-item span {
+    flex: 1;
+    text-align: left;
+}
+
+.menu-item svg {
+    opacity: 0.7;
+}
+
+.menu-item.delete {
+    color: #ef4444;
+}
+
+.menu-item.delete:hover {
+    background: rgba(239, 68, 68, 0.1);
+}
+
+.menu-item.delete svg {
+    opacity: 1;
+}
+
+.menu-separator {
+    height: 1px;
+    background: var(--border-sidebar, rgba(0, 0, 0, 0.05));
+    margin: 4px 6px;
+}
+
+.dark .menu-separator {
+    background: rgba(255, 255, 255, 0.08);
+}
+
+.sidebar-toggle,
+.icon-btn {
+    background: transparent;
+    border: none;
+    color: var(--text-secondary);
+    cursor: pointer;
+    padding: 0.5rem;
+    border-radius: 0.5rem;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    transition: transform 0.2s, opacity 0.2s;
+}
+
+.sidebar-toggle:hover,
+.icon-btn:hover {
+    background: var(--bg-surface-hover);
+    color: var(--text-primary);
+}
+
+/* Removed old new-chat-btn styles as they are now unified under .nav-item */
+
+.conversations-list {
+    flex: 1;
+    overflow-y: auto;
+    padding: 0.5rem 0.75rem;
+    margin-top: 0.5rem;
+}
+
+.conversation-item {
+    display: flex;
+    align-items: center;
+    gap: 0.75rem;
+    padding: 0.6rem 0.75rem;
+    border-radius: 0.5rem;
+    cursor: pointer;
+    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
+    position: relative;
+    border: 1px solid transparent;
+    margin-bottom: 2px;
+}
+
+.conv-icon-container {
+    position: relative;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+}
+
+.pin-hint-icon {
+    position: absolute;
+    top: -5px;
+    right: -5px;
+    background: var(--brand-primary);
+    color: white;
+    border-radius: 50%;
+    padding: 1px;
+    border: 1px solid var(--bg-surface);
+}
+
+.sidebar-section-header {
+    font-size: 0.7rem;
+    font-weight: 600;
+    text-transform: uppercase;
+    letter-spacing: 0.05em;
+    color: var(--text-secondary);
+    padding: 1rem 0.75rem 0.5rem;
+    opacity: 0.6;
+}
+
+.sidebar-archived-toggle {
+    display: flex;
+    align-items: center;
+    gap: 0.6rem;
+    padding: 0.75rem;
+    margin: 0.5rem 0.75rem;
+    background: rgba(var(--bg-canvas-rgb), 0.3);
+    border-radius: 0.5rem;
+    cursor: pointer;
+    font-size: 0.8rem;
+    color: var(--text-secondary);
+    transition: all 0.2s;
+    border: 1px dashed var(--border-light);
+}
+
+.sidebar-archived-toggle:hover {
+    background: var(--bg-surface-hover);
+    color: var(--text-primary);
+    border-style: solid;
+}
+
+.conversation-item:hover {
+    background: var(--bg-surface-hover);
+}
+
+.conversation-item.active {
+    background: var(--brand-light);
+    /* Tint active item */
+    border-color: rgba(99, 102, 241, 0.1);
+    /* Subtle color border */
+}
+
+/* In dark mode we might want a different active state */
+.dark .conversation-item.active {
+    background: rgba(255, 255, 255, 0.05);
+    border-color: rgba(255, 255, 255, 0.05);
+}
+
+.conversation-title {
+    flex: 1;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+    font-size: 0.875rem;
+    color: var(--text-secondary);
+}
+
+.conversation-item.active .conversation-title {
+    color: var(--text-primary);
+    font-weight: 500;
+}
+
+.edit-title-input {
+    flex: 1;
+    background: var(--bg-canvas);
+    border: 1px solid var(--brand-primary);
+    border-radius: 0.25rem;
+    padding: 0.25rem 0.5rem;
+    font-size: 0.875rem;
+    color: var(--text-primary);
+    outline: none;
+}
+
+.menu-btn {
+    opacity: 0;
+    transition: opacity 0.2s;
+    padding: 0.25rem;
+    border-radius: 0.25rem;
+    color: var(--text-tertiary);
+    background: none;
+    border: none;
+    cursor: pointer;
+}
+
+.conversation-item:hover .menu-btn,
+.conversation-item.active .menu-btn {
+    opacity: 1;
+}
+
+.menu-btn:hover {
+    color: var(--text-primary);
+    background: var(--bg-surface-hover);
+}
+
+/* Legacy footer removed */
+
+.theme-toggle:hover {
+    background: var(--bg-surface-hover);
+    color: var(--text-primary);
+    border-color: var(--border-medium);
+}
+
+/* Context Menu */
+.context-menu {
+    position: absolute;
+    right: 0.5rem;
+    top: 80%;
+    background: rgba(var(--bg-canvas-rgb), 0.98);
+    backdrop-filter: blur(24px);
+    border: 1px solid var(--border-light);
+    border-radius: 0.5rem;
+    box-shadow: var(--shadow-lg);
+    z-index: 1000;
+    min-width: 140px;
+    padding: 0.25rem;
+    animation: popIn 0.15s cubic-bezier(0.16, 1, 0.3, 1);
+}
+
+.dark .context-menu {
+    background: rgba(18, 18, 21, 0.98);
+    border-color: rgba(255, 255, 255, 0.12);
+}
+
+.context-menu button {
+    width: 100%;
+    display: flex;
+    align-items: center;
+    gap: 0.5rem;
+    padding: 0.5rem 0.75rem;
+    background: none;
+    border: none;
+    cursor: pointer;
+    font-size: 0.875rem;
+    color: var(--text-primary);
+    border-radius: 0.25rem;
+    transition: background 0.15s;
+}
+
+.context-menu button:hover {
+    background: var(--bg-surface-hover);
+}
+
+.context-menu button.danger {
+    color: var(--status-error);
+}
+
+.context-menu button.danger:hover {
+    background: rgba(239, 68, 68, 0.1);
+}
+
+.context-menu .divider {
+    height: 1px;
+    background: var(--border-light);
+    margin: 0.25rem 0;
+}
+
+/* Premium Rename Input */
+.premium-rename-input {
+    width: 100%;
+    padding: 0.25rem 0.6rem;
+    background: rgba(var(--bg-surface-rgb), 0.5);
+    backdrop-filter: blur(8px);
+    border: 1px solid var(--brand-primary);
+    border-radius: 0.5rem;
+    color: var(--text-primary);
+    font-family: inherit;
+    font-size: inherit;
+    outline: none;
+    box-shadow: 0 0 0 2px rgba(99, 102, 241, 0.15);
+    transition: all 0.2s ease;
+}
+
+.premium-rename-input:focus {
+    background: var(--bg-surface);
+    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.25), var(--shadow-glow);
+}
+
+.dark .premium-rename-input {
+    background: rgba(var(--bg-surface-rgb), 0.3);
+    border-color: var(--brand-primary);
+}
+
+.header-rename-input {
+    max-width: 250px;
+    height: 32px;
+    font-weight: 600;
+}
+
+@media (max-width: 768px) {
+    .header-rename-input {
+        max-width: 150px;
+    }
+}
+
+/* Truly Centered Opaque Rename Modal - Scoped to Main Content */
+.rename-modal-overlay {
+    position: absolute;
+    /* Scoped to .main-content */
+    top: 60px;
+    /* Below Header */
+    left: 0;
+    right: 0;
+    bottom: 0;
+    background: rgba(0, 0, 0, 0.05);
+    /* Very light overlay, no blur to keep header sharp */
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    z-index: 1500;
+    animation: fadeIn 0.3s ease-out;
+}
+
+.rename-modal-content {
+    background: var(--bg-canvas);
+    /* Opaque background */
+    width: 90%;
+    max-width: 440px;
+    padding: 2.25rem;
+    border-radius: 1.5rem;
+    border: 1px solid var(--border-light);
+    box-shadow: 0 30px 60px -12px rgba(0, 0, 0, 0.3);
+    animation: modalPop 0.4s cubic-bezier(0.16, 1, 0.3, 1);
+    position: relative;
+    overflow: hidden;
+    margin-top: -30px;
+    /* Offset the top:60px to center truly in the available session space */
+}
+
+.dark .rename-modal-content {
+    background: #18181b;
+    /* Zinc 900 - Opaque */
+    border-color: rgba(255, 255, 255, 0.1);
+}
+
+.rename-modal-title {
+    font-size: 1.25rem;
+    font-weight: 800;
+    margin-bottom: 1.25rem;
+    color: var(--text-primary);
+    font-family: 'Outfit', sans-serif;
+    letter-spacing: -0.02em;
+}
+
+.rename-modal-actions {
+    display: flex;
+    justify-content: flex-end;
+    gap: 0.875rem;
+    margin-top: 2rem;
+}
+
+.modal-btn {
+    padding: 0.7rem 1.75rem;
+    border-radius: 0.75rem;
+    font-size: 0.95rem;
+    font-weight: 600;
+    cursor: pointer;
+    transition: all 0.25s ease-in-out;
+    border: none;
+    font-family: 'Outfit', sans-serif;
+    letter-spacing: 0.01em;
+}
+
+.modal-btn:active {
+    transform: scale(0.98);
+}
+
+.modal-btn-cancel {
+    background: var(--bg-surface-hover);
+    color: var(--text-secondary);
+}
+
+.modal-btn-cancel:hover {
+    background: var(--border-light);
+    color: var(--text-primary);
+}
+
+.modal-btn-save {
+    background: var(--brand-primary);
+    color: white;
+    box-shadow: 0 4px 12px rgba(var(--brand-primary-rgb), 0.2);
+}
+
+.modal-btn-save:hover {
+    background: var(--brand-hover);
+    box-shadow: 0 6px 16px rgba(var(--brand-primary-rgb), 0.3);
+}
+
+@keyframes fadeIn {
+    from {
+        opacity: 0;
+    }
+
+    to {
+        opacity: 1;
+    }
+}
+
+@keyframes modalPop {
+    from {
+        opacity: 0;
+        transform: translateY(24px) scale(0.96);
+    }
+
+    to {
+        opacity: 1;
+        transform: translateY(0) scale(1);
+    }
+}
+
+/* ========================================
+   Main Content
+   ======================================== */
+.main-content {
+    flex: 1;
+    display: flex;
+    flex-direction: column;
+    min-width: 0;
+    height: 100%;
+    position: relative;
+    background: var(--bg-canvas);
+    overflow-x: hidden;
+    /* Prevent horizontal scroll on main area */
+}
+
+.top-bar {
+    display: none;
+    /* Desktop default */
+    padding: 0.75rem 1rem;
+    border-bottom: 1px solid var(--border-light);
+    align-items: center;
+    gap: 0.5rem;
+    background: var(--bg-canvas);
+}
+
+/* Loading Bar */
+.loading-bar {
+    height: 2px;
+    width: 100%;
+    background: var(--bg-surface);
+    overflow: hidden;
+    position: absolute;
+    top: 0;
+    left: 0;
+    z-index: 50;
+}
+
+.loading-progress {
+    height: 100%;
+    width: 30%;
+    background: linear-gradient(90deg, var(--brand-primary), var(--brand-hover));
+    animation: loading 1.5s ease-in-out infinite;
+}
+
+@keyframes loading {
+    0% {
+        transform: translateX(-100%);
+    }
+
+    100% {
+        transform: translateX(400%);
+    }
+}
+
+/* ========================================
+   Messages Area
+   ======================================== */
+.messages-container {
+    flex: 1;
+    overflow-y: auto;
+    display: flex;
+    flex-direction: column;
+    /* scroll-behavior is now handled dynamically in JavaScript to prevent jumps during session switching */
+    padding-bottom: 2rem;
+    overflow-anchor: none;
+    overflow-x: hidden;
+    scrollbar-gutter: stable;
+    overscroll-behavior: contain;
+}
+
+.messages-container.transitioning {
+    opacity: 0;
+    pointer-events: none;
+    transition: opacity 0.1s ease-out;
+    /* Chỉ chuyển động mờ ảo khi chuyển session */
+}
+
+/* Container for messages and fixed elements like scroll-to-bottom */
+.messages-section {
+    flex: 1;
+    min-height: 0;
+    /* Important for flex child with overflow */
+    position: relative;
+    display: flex;
+    flex-direction: column;
+}
+
+/* Specific spotlight for tour to prevent it being too large */
+.tour-chat-spotlight {
+    position: absolute;
+    top: 50%;
+    left: 50%;
+    transform: translate(-50%, -50%);
+    width: 80%;
+    height: 75%;
+    pointer-events: none;
+    z-index: -1;
+    visibility: hidden;
+}
+
+/* Welcome Screen */
+.welcome-screen {
+    flex: 1;
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    text-align: center;
+    padding: 2rem;
+    max-width: 800px;
+    margin: 0 auto;
+    width: 100%;
+    animation: fadeIn 0.5s ease-out;
+}
+
+.welcome-icon {
+    margin-bottom: 2rem;
+    filter: drop-shadow(0 10px 15px rgba(99, 102, 241, 0.2));
+}
+
+.welcome-icon img {
+    height: 80px;
+    width: auto;
+}
+
+.welcome-screen h2 {
+    font-family: 'Outfit', sans-serif;
+    font-size: 2.5rem;
+    margin-bottom: 1.25rem;
+    font-weight: 800;
+    line-height: 1.1;
+    background: linear-gradient(135deg, var(--text-primary) 20%, #6366f1);
+    -webkit-background-clip: text;
+    background-clip: text;
+    -webkit-text-fill-color: transparent;
+    letter-spacing: -0.04em;
+}
+
+.welcome-screen p {
+    color: var(--text-secondary);
+    margin-bottom: 2.5rem;
+    line-height: 1.6;
+    font-size: 1.1rem;
+    max-width: 600px;
+}
+
+.example-prompts {
+    display: grid;
+    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
+    gap: 1rem;
+    width: 100%;
+    max-width: 800px;
+}
+
+.example-prompts button {
+    padding: 1rem;
+    background: var(--bg-surface);
+    border: 1px solid var(--border-light);
+    border-radius: 0.75rem;
+    cursor: pointer;
+    font-size: 0.9rem;
+    color: var(--text-secondary);
+    text-align: left;
+    transition: transform 0.2s, box-shadow 0.2s, opacity 0.2s;
+    line-height: 1.5;
+}
+
+.example-prompts button:hover {
+    background: var(--bg-canvas);
+    border-color: var(--brand-primary);
+    color: var(--text-primary);
+    transform: translateY(-2px);
+    box-shadow: var(--shadow-md);
+}
+
+/* Messages - Breathable ChatGPT Layout */
+.message {
+    display: flex;
+    gap: 0;
+    padding: 1rem 1rem 1.25rem;
+    /* More compact vertical padding */
+    max-width: 800px;
+    /* ChatGPT standard width */
+    width: 100%;
+    margin: 0 auto;
+    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
+    position: relative;
+    border-bottom: 1px solid transparent;
+    /* Ready for dividers if needed */
+}
+
+.message:hover {
+    background: transparent;
+    /* Remove hover background for a cleaner feel */
+}
+
+/* User Message - Mirrored to right */
+.message.user {
+    flex-direction: row-reverse;
+    background: transparent;
+}
+
+.message.user .message-body {
+    text-align: right;
+    display: flex;
+    flex-direction: column;
+    align-items: flex-end;
+}
+
+.message.user .message-content {
+    text-align: left;
+    background: #f4f4f4;
+    /* Minimalist ChatGPT light grey */
+    padding: 12px 20px;
+    /* Refined ChatGPT-like padding */
+    border-radius: 1.5rem;
+    /* Fully rounded ChatGPT style */
+    display: block;
+    width: fit-content;
+    /* Trải chữ ra trước, bọc màu sau */
+    max-width: 75%;
+    /* Giới hạn tối đa 3/4 khu vực chat */
+    min-width: 40px;
+    box-shadow: none;
+    /* No shadow for flat look */
+    word-break: break-word;
+    white-space: pre-wrap;
+    align-self: flex-end;
+}
+
+.dark .message.user .message-content {
+    background: #2f2f2f;
+    /* Deep grey for dark mode ChatGPT style */
+}
+
+.message.user .message-footer {
+    justify-content: flex-end;
+    /* Căn nút sang phải cho người dùng */
+}
+
+.message.user .copy-toast {
+    left: auto;
+    right: 0;
+}
+
+/* Assistant Message - Open & Frameless */
+.message.assistant {
+    background: transparent;
+    border: none;
+    box-shadow: none;
+    margin-top: 0;
+    margin-bottom: 0;
+}
+
+.message-avatar {
+    width: 2.5rem;
+    height: 2.5rem;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    flex-shrink: 0;
+    border-radius: 0.75rem;
+    background: var(--bg-surface);
+    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.05);
+    transition: transform 0.2s;
+}
+
+.message:hover .message-avatar {
+    transform: scale(1.05);
+}
+
+.message.user .message-avatar {
+    background: linear-gradient(135deg, #f1f5f9, #e2e8f0);
+    color: #64748b;
+    border: 1px solid rgba(0, 0, 0, 0.05);
+}
+
+.message.assistant .message-avatar {
+    background: linear-gradient(135deg, var(--brand-primary), #818cf8);
+    color: white;
+    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
+}
+
+.message-body {
+    flex: 1;
+    min-width: 0;
+}
+
+/* Floating Message Actions - Minimalist ChatGPT Style */
+.message-footer {
+    position: relative;
+    /* Moved back into flow */
+    margin-top: 8px;
+    display: flex;
+    align-items: center;
+    gap: 0.25rem;
+    opacity: 0;
+    transition: all 0.2s ease;
+    z-index: 1;
+    width: 100%;
+}
+
+.message:hover .message-footer {
+    opacity: 1;
+    transform: translateY(0) scale(1);
+}
+
+.footer-actions-right {
+    display: flex;
+    gap: 0.25rem;
+}
+
+.footer-btn {
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    background: transparent;
+    /* No background by default */
+    border: none;
+    /* No border */
+    color: var(--text-tertiary);
+    cursor: pointer;
+    padding: 6px;
+    border-radius: 6px;
+    transition: all 0.15s ease;
+    box-shadow: none;
+    position: relative;
+    /* Crucial for toast positioning */
+}
+
+.footer-btn:hover {
+    background: rgba(var(--brand-primary-rgb), 0.08);
+    /* Subtle hover bg */
+    color: var(--brand-primary);
+}
+
+.footer-btn svg {
+    color: var(--text-tertiary);
+    transition: color 0.2s;
+}
+
+.footer-btn:hover svg {
+    color: var(--brand-primary);
+}
+
+.footer-btn.expand-toggle {
+    color: var(--brand-primary);
+}
+
+.footer-btn.expand-toggle:hover {
+    background: rgba(var(--brand-primary-rgb), 0.12);
+}
+
+.footer-btn.copy-btn.copied {
+    color: var(--status-success);
+}
+
+/* Export Dropdown */
+.export-dropdown-wrapper {
+    position: relative;
+}
+
+.export-menu {
+    position: absolute;
+    bottom: calc(100% + 8px);
+    left: 0;
+    background: var(--bg-surface);
+    border: 1px solid var(--border-light);
+    border-radius: 0.75rem;
+    box-shadow: var(--shadow-lg);
+    padding: 0.5rem;
+    min-width: 160px;
+    z-index: 100;
+    display: flex;
+    flex-direction: column;
+    gap: 2px;
+    animation: menuSmoothEntryUp 0.2s cubic-bezier(0.16, 1, 0.3, 1);
+}
+
+.message.user .export-menu {
+    left: auto;
+    right: 0;
+}
+
+.export-menu button {
+    display: flex;
+    align-items: center;
+    gap: 0.75rem;
+    padding: 0.5rem 0.75rem;
+    background: transparent;
+    border: none;
+    border-radius: 0.5rem;
+    color: var(--text-secondary);
+    font-size: 0.85rem;
+    cursor: pointer;
+    transition: all 0.2s;
+    text-align: left;
+    white-space: nowrap;
+}
+
+.export-menu button:hover {
+    background: var(--bg-surface-hover);
+    color: var(--text-primary);
+}
+
+.export-menu button svg {
+    color: var(--text-tertiary);
+}
+
+.export-menu button:hover svg {
+    color: var(--brand-primary);
+}
+
+.copy-toast {
+    position: absolute;
+    bottom: calc(100% + 4px);
+    /* Move closer to icon */
+    left: 50%;
+    transform: translateX(-50%);
+    background: var(--brand-primary);
+    color: white;
+    padding: 2px 8px;
+    /* Slimmer toast */
+    border-radius: 4px;
+    font-size: 0.65rem;
+    font-weight: 600;
+    white-space: nowrap;
+    animation: premiumToast 1.8s cubic-bezier(0.16, 1, 0.3, 1) forwards;
+    pointer-events: none;
+    z-index: 100;
+    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3), var(--shadow-glow);
+    letter-spacing: 0.01em;
+}
+
+@keyframes premiumToast {
+    0% {
+        opacity: 0;
+        transform: translate(-50%, 12px) scale(0.8);
+    }
+
+    15% {
+        opacity: 1;
+        transform: translate(-50%, 0) scale(1.05);
+    }
+
+    20% {
+        opacity: 1;
+        transform: translate(-50%, 0) scale(1);
+    }
+
+    85% {
+        opacity: 1;
+        transform: translate(-50%, 0) scale(1);
+    }
+
+    100% {
+        opacity: 0;
+        transform: translate(-50%, -20px) scale(0.9);
+    }
+}
+
+.message-actions button.copied {
+    color: var(--status-success) !important;
+    background: rgba(16, 185, 129, 0.1) !important;
+    border-radius: 0.25rem;
+}
+
+.message-actions button.copied svg {
+    animation: successPop 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
+    filter: drop-shadow(0 0 4px rgba(16, 185, 129, 0.4));
+}
+
+@keyframes successPop {
+    0% {
+        transform: scale(0.5) rotate(-20deg);
+        opacity: 0;
+    }
+
+    50% {
+        transform: scale(1.2) rotate(10deg);
+    }
+
+    100% {
+        transform: scale(1) rotate(0);
+        opacity: 1;
+    }
+}
+
+/* Streaming cursor - ChatGPT style */
+.message.assistant.streaming .message-content::after {
+    content: '';
+    display: inline-block;
+    width: 6px;
+    height: 1.1em;
+    background-color: var(--brand-primary);
+    vertical-align: middle;
+    margin-left: 4px;
+    border-radius: 1px;
+    animation: cursor-blink 0.8s s-curve infinite;
+}
+
+@keyframes cursor-blink {
+
+    0%,
+    100% {
+        opacity: 1;
+    }
+
+    50% {
+        opacity: 0;
+    }
+}
+
+/* Smooth fade-in for streamed text bits */
+.message.assistant.streaming .message-content p {
+    display: inline;
+}
+
+/* Collapsible Content */
+.collapsible-content {
+    width: 100%;
+    display: flex;
+    flex-direction: column;
+}
+
+.message.user .collapsible-content {
+    align-items: flex-end;
+}
+
+.collapsible-content.truncated .content-inner {
+    position: relative;
+    mask-image: linear-gradient(to bottom, black 50%, transparent 100%);
+    -webkit-mask-image: linear-gradient(to bottom, black 50%, transparent 100%);
+}
+
+/* Collapsible Content - Fade effect refined */
+.collapsible-content.truncated .content-inner {
+    position: relative;
+    mask-image: linear-gradient(to bottom, black 60%, transparent 100%);
+    -webkit-mask-image: linear-gradient(to bottom, black 60%, transparent 100%);
+}
+
+/* ========================================
+   Input Container
+   ======================================== */
+.input-container {
+    padding: 1rem 1.5rem 2rem;
+    max-width: 850px;
+    margin: 0 auto;
+    width: 100%;
+    flex-shrink: 0;
+    background: linear-gradient(to top, var(--bg-canvas) 80%, transparent);
+    /* Fade out top */
+}
+
+.input-wrapper {
+    display: flex;
+    align-items: center;
+    gap: 0.75rem;
+    background: rgba(var(--bg-surface-rgb), 0.7);
+    backdrop-filter: blur(24px) saturate(160%);
+    -webkit-backdrop-filter: blur(24px) saturate(160%);
+    border: 1px solid var(--border-light);
+    border-radius: 1.25rem;
+    padding: 0.75rem 1rem;
+    transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.3s cubic-bezier(0.16, 1, 0.3, 1), box-shadow 0.3s cubic-bezier(0.16, 1, 0.3, 1);
+    /* Exclude color/background/border from transition to prevent flickering on theme switch */
+    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.04), var(--shadow-sm);
+    position: relative;
+    z-index: 10;
+}
+
+.input-wrapper:focus-within {
+    border-color: var(--brand-primary);
+    background: rgba(var(--bg-canvas-rgb), 0.9);
+    box-shadow: 0 12px 40px rgba(99, 102, 241, 0.1);
+}
+
+.drag-overlay {
+    position: absolute;
+    inset: 0;
+    background: rgba(var(--brand-primary-rgb, 99, 102, 241), 0.1);
+    backdrop-filter: blur(12px);
+    -webkit-backdrop-filter: blur(12px);
+    z-index: 50;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    border-radius: 1rem;
+    border: 2px dashed var(--brand-primary);
+    pointer-events: none;
+    animation: fadeIn 0.2s ease-out;
+}
+
+.drag-content {
+    display: flex;
+    align-items: center;
+    gap: 0.75rem;
+    padding: 0 1rem;
+}
+
+.drag-icon {
+    color: var(--brand-primary);
+    animation: pulseGlow 1.5s infinite ease-in-out;
+}
+
+.drag-text {
+    font-family: 'Outfit', sans-serif;
+    font-size: 0.95rem;
+    font-weight: 500;
+    color: var(--brand-primary);
+    letter-spacing: 0.025em;
+}
+
+@keyframes pulseGlow {
+    0% {
+        transform: scale(1);
+        opacity: 0.8;
+        filter: drop-shadow(0 0 0px var(--brand-primary));
+    }
+
+    50% {
+        transform: scale(1.1);
+        opacity: 1;
+        filter: drop-shadow(0 0 8px var(--brand-primary));
+    }
+
+    100% {
+        transform: scale(1);
+        opacity: 0.8;
+        filter: drop-shadow(0 0 0px var(--brand-primary));
+    }
+}
+
+/* Dark mode specific overlay refinement */
+.dark .drag-overlay {
+    background: rgba(0, 0, 0, 0.4);
+    border-color: var(--brand-primary);
+}
+
+.attach-btn {
+    width: 2.25rem;
+    height: 2.25rem;
+    border-radius: 50%;
+    background: transparent;
+    border: none;
+    color: var(--text-secondary);
+    cursor: pointer;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    transition: all 0.2s;
+}
+
+.attach-btn:hover {
+    background: var(--bg-surface-hover);
+    color: var(--text-primary);
+}
+
+.input-wrapper textarea {
+    flex: 1;
+    background: transparent;
+    border: none;
+    outline: none;
+    resize: none;
+    color: var(--text-primary);
+    font-family: inherit;
+    font-size: 1rem;
+    line-height: 1.5;
+    padding: 0.35rem 0.25rem;
+    max-height: 200px;
+    min-height: 24px;
+}
+
+.input-wrapper textarea::placeholder {
+    color: var(--text-tertiary);
+}
+
+.send-btn {
+    width: 2.25rem;
+    height: 2.25rem;
+    border-radius: 0.5rem;
+    /* Rounded rect looks more modern than circle sometimes, but let's stick to circle or soft square */
+    border-radius: 50%;
+    background: var(--brand-primary);
+    color: white;
+    border: none;
+    cursor: pointer;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    transition: transform 0.2s, opacity 0.2s, box-shadow 0.2s;
+    /* Exclude color/background from transition to prevent flickering on theme switch */
+    flex-shrink: 0;
+}
+
+.send-btn:hover:not(:disabled) {
+    background: var(--brand-hover);
+    transform: scale(1.05);
+}
+
+.send-btn:disabled {
+    background: var(--bg-surface-hover);
+    color: var(--text-tertiary);
+    cursor: not-allowed;
+}
+
+.input-hint {
+    text-align: center;
+    font-size: 0.75rem;
+    color: var(--text-tertiary);
+    margin-top: 0.75rem;
+}
+
+/* Upload Previews */
+/* Image Attachment Area */
+.image-attachment-area {
+    background: rgba(var(--bg-surface-rgb), 0.6);
+    backdrop-filter: blur(8px);
+    -webkit-backdrop-filter: blur(8px);
+    border: 1px solid var(--border-light);
+    border-radius: 1rem;
+    padding: 0.75rem;
+    margin-bottom: 0.75rem;
+    animation: slideUp 0.3s ease-out;
+}
+
+.attachment-header {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    margin-bottom: 0.5rem;
+    padding-bottom: 0.5rem;
+    border-bottom: 1px solid var(--border-light);
+}
+
+.attachment-counter {
+    font-size: 0.8rem;
+    color: var(--text-secondary);
+}
+
+.attachment-counter strong {
+    color: var(--brand-primary);
+}
+
+.clear-all-btn {
+    background: transparent;
+    border: none;
+    color: var(--status-error);
+    font-size: 0.75rem;
+    font-weight: 500;
+    cursor: pointer;
+    padding: 2px 6px;
+    border-radius: 4px;
+    transition: background 0.2s;
+}
+
+.clear-all-btn:hover {
+    background: rgba(239, 68, 68, 0.1);
+    /* Based on status-error red */
+}
+
+.uploaded-images-preview {
+    display: flex;
+    gap: 0.75rem;
+    overflow-x: auto;
+    padding: 0.25rem 0;
+    scrollbar-width: thin;
+}
+
+.preview-item {
+    position: relative;
+    width: 72px;
+    height: 72px;
+    flex-shrink: 0;
+    border-radius: 0.75rem;
+    overflow: hidden;
+    border: 2px solid var(--bg-surface);
+    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
+    background: var(--bg-canvas);
+    transition: transform 0.2s cubic-bezier(0.16, 1, 0.3, 1);
+}
+
+.preview-item.clickable {
+    cursor: pointer;
+}
+
+.preview-item.clickable:hover {
+    transform: scale(1.05);
+}
+
+/* Message Image Previews (Compact) */
+.message-images-list {
+    display: flex;
+    gap: 0.75rem;
+    margin-bottom: 0.25rem;
+    overflow-x: auto;
+    padding-bottom: 4px;
+    /* Tiny bit of room for shadow/border */
+    scrollbar-width: none;
+    max-width: 100%;
+}
+
+/* Bring text closer to images when they exist - but not squashed, and keep it centered */
+.message-images-list+.collapsible-content .message-content {
+    padding: 10px 20px !important;
+}
+
+.message-images-list+.collapsible-content .message-content p:first-child {
+    margin-top: 0 !important;
+}
+
+.message-images-list::-webkit-scrollbar {
+    display: none;
+}
+
+.message-image-preview {
+    position: relative;
+    width: 84px;
+    height: 84px;
+    flex-shrink: 0;
+    border-radius: 0.75rem;
+    overflow: hidden;
+    border: 1px solid var(--border-light);
+    box-shadow: var(--shadow-sm);
+    cursor: pointer;
+    background: var(--bg-surface);
+    transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
+}
+
+.message-image-preview:hover {
+    transform: scale(1.05);
+    border-color: var(--brand-primary);
+    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.15);
+}
+
+.message-image-preview img {
+    width: 100%;
+    height: 100%;
+    object-fit: cover;
+    transition: opacity 0.2s;
+}
+
+.message-image-preview:hover img {
+    opacity: 0.9;
+}
+
+.remove-img-btn {
+    position: absolute;
+    top: 4px;
+    right: 4px;
+    background: rgba(0, 0, 0, 0.6);
+    backdrop-filter: blur(4px);
+    color: white;
+    border: none;
+    border-radius: 50%;
+    width: 20px;
+    height: 20px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    cursor: pointer;
+    transition: all 0.2s;
+    z-index: 2;
+}
+
+.remove-img-btn:hover {
+    background: #ef4444;
+    /* status-error */
+    transform: scale(1.1);
+}
+
+/* Error Toast */
+.upload-error-toast {
+    position: absolute;
+    bottom: calc(100% + 1rem);
+    left: 50%;
+    transform: translateX(-50%);
+    background: #ef4444;
+    color: white;
+    padding: 0.5rem 1rem;
+    border-radius: 2rem;
+    font-size: 0.85rem;
+    font-weight: 500;
+    white-space: nowrap;
+    box-shadow: var(--shadow-lg);
+    z-index: 100;
+    animation: fadeInUp 0.3s ease-out;
+}
+
+@keyframes slideUp {
+    from {
+        opacity: 0;
+        transform: translateY(10px);
+    }
+
+    to {
+        opacity: 1;
+        transform: translateY(0);
+    }
+}
+
+/* Premium Image Viewer Overlay - Ultra-thin and blurred */
+.premium-viewer-overlay {
+    position: fixed;
+    inset: 0;
+    background: rgba(var(--bg-canvas-rgb), 0.15);
+    /* Even thinner background */
+    backdrop-filter: blur(60px) saturate(200%);
+    /* Consistent saturation for color vibrance */
+    -webkit-backdrop-filter: blur(60px) saturate(200%);
+    z-index: 2000;
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    animation: fadeInOverlay 0.6s cubic-bezier(0.16, 1, 0.3, 1);
+    padding: 2rem;
+}
+
+.premium-viewer-overlay.is-restored {
+    animation: none !important;
+}
+
+@keyframes fadeInOverlay {
+    from {
+        opacity: 0;
+        backdrop-filter: blur(0px);
+    }
+
+    to {
+        opacity: 1;
+        backdrop-filter: blur(60px) saturate(200%);
+        -webkit-backdrop-filter: blur(60px) saturate(200%);
+    }
+}
+
+.viewer-top-bar {
+    position: absolute;
+    top: 1.5rem;
+    left: 1.5rem;
+    right: 1.5rem;
+    height: 64px;
+    background: rgba(var(--bg-surface-rgb), 0.4);
+    border: 1px solid var(--border-light);
+    border-radius: 1.25rem;
+    backdrop-filter: blur(24px) saturate(160%);
+    -webkit-backdrop-filter: blur(24px) saturate(160%);
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    padding: 0 1.5rem;
+    z-index: 2010;
+    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.08), var(--shadow-sm);
+}
+
+.viewer-info {
+    color: var(--text-primary);
+    font-size: 0.95rem;
+    font-weight: 600;
+    font-family: 'Outfit', sans-serif;
+    letter-spacing: 0.02em;
+}
+
+.viewer-actions {
+    display: flex;
+    align-items: center;
+    gap: 0.5rem;
+}
+
+.viewer-actions button {
+    background: transparent;
+    border: 1px solid transparent;
+    color: var(--text-secondary);
+    width: 40px;
+    height: 40px;
+    border-radius: 12px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    cursor: pointer;
+    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
+}
+
+.viewer-actions button:hover {
+    background: var(--bg-surface-hover);
+    color: var(--brand-primary);
+    border-color: var(--border-light);
+    transform: none;
+    /* Removed jumpy translateY */
+}
+
+.viewer-divider {
+    width: 1px;
+    height: 24px;
+    background: var(--border-light);
+    margin: 0 0.5rem;
+}
+
+.viewer-close-btn {
+    background: rgba(var(--status-error-rgb, 239, 68, 68), 0.1) !important;
+    color: var(--status-error) !important;
+}
+
+.viewer-close-btn:hover {
+    background: var(--status-error) !important;
+    color: white !important;
+    border-color: transparent !important;
+}
+
+.viewer-image-container {
+    flex: 1;
+    width: 100%;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    overflow: hidden;
+    margin: 4rem 0;
+    position: relative;
+}
+
+/* Layered glows for depth and theme coordination */
+.viewer-image-container::before {
+    content: '';
+    position: absolute;
+    width: 80%;
+    height: 80%;
+    background: radial-gradient(circle, rgba(99, 102, 241, 0.15) 0%, transparent 60%);
+    pointer-events: none;
+    z-index: -1;
+    animation: pulseGlowViewer 8s infinite alternate ease-in-out;
+}
+
+.viewer-image-container::after {
+    content: '';
+    position: absolute;
+    width: 100%;
+    height: 100%;
+    background: radial-gradient(circle at 50% 50%, rgba(var(--brand-primary-rgb), 0.05) 0%, transparent 80%);
+    pointer-events: none;
+    z-index: -1;
+}
+
+@keyframes pulseGlowViewer {
+    0% {
+        transform: scale(1) opacity(0.5);
+    }
+
+    100% {
+        transform: scale(1.2) opacity(0.8);
+    }
+}
+
+.viewer-main-image {
+    max-width: 90vw;
+    max-height: 75vh;
+    object-fit: contain;
+    border-radius: 1.5rem;
+    border: 1px solid rgba(var(--brand-primary-rgb), 0.1);
+    box-shadow: 0 40px 100px rgba(0, 0, 0, 0.3), 0 0 40px rgba(var(--brand-primary-rgb), 0.1);
+    user-select: none;
+    pointer-events: auto;
+    background: var(--bg-canvas);
+    transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
+}
+
+/* Nav Buttons */
+.viewer-nav-btn {
+    position: absolute;
+    top: 50%;
+    transform: translateY(-50%);
+    background: rgba(var(--bg-surface-rgb), 0.6);
+    border: 1px solid var(--border-light);
+    color: var(--text-primary);
+    width: 64px;
+    height: 64px;
+    border-radius: 50%;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    cursor: pointer;
+    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
+    z-index: 2005;
+    backdrop-filter: blur(12px);
+    -webkit-backdrop-filter: blur(12px);
+    box-shadow: var(--shadow-md);
+}
+
+.viewer-nav-btn:hover {
+    background: var(--brand-primary);
+    color: white;
+    border-color: transparent;
+    box-shadow: 0 0 20px rgba(var(--brand-primary-rgb), 0.3);
+}
+
+.viewer-nav-btn:active {
+    scale: 0.95;
+}
+
+.viewer-nav-btn.prev {
+    left: 2rem;
+}
+
+.viewer-nav-btn.next {
+    right: 2rem;
+}
+
+/* Thumbnails Strip */
+.viewer-thumbnails-strip {
+    position: absolute;
+    bottom: 2rem;
+    left: 50%;
+    transform: translateX(-50%);
+    display: flex;
+    gap: 0.75rem;
+    padding: 0.65rem;
+    background: rgba(var(--bg-surface-rgb), 0.6);
+    backdrop-filter: blur(24px) saturate(160%);
+    -webkit-backdrop-filter: blur(24px) saturate(160%);
+    border: 1px solid var(--border-light);
+    border-radius: 1.25rem;
+    z-index: 2010;
+    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.12), var(--shadow-sm);
+}
+
+.viewer-thumb-item {
+    width: 52px;
+    height: 52px;
+    border-radius: 10px;
+    overflow: hidden;
+    cursor: pointer;
+    border: 2px solid transparent;
+    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
+    opacity: 0.5;
+    background: var(--bg-canvas);
+}
+
+.viewer-thumb-item:hover {
+    opacity: 1;
+    transform: translateY(-4px) scale(1.1);
+}
+
+.viewer-thumb-item.active {
+    opacity: 1;
+    border-color: var(--brand-primary);
+    box-shadow: 0 0 15px rgba(var(--brand-primary-rgb), 0.4);
+    transform: translateY(-4px) scale(1.1);
+}
+
+.viewer-thumb-item img {
+    width: 100%;
+    height: 100%;
+    object-fit: cover;
+}
+
+@keyframes fadeIn {
+    from {
+        opacity: 0;
+    }
+
+    to {
+        opacity: 1;
+    }
+}
+
+/* === ChatGPT-Style Sidebar Redesign === */
+.sidebar-container {
+    width: 260px;
+    height: 100vh;
+    background: var(--bg-sidebar);
+    border-right: 1px solid var(--border-light);
+    display: flex;
+    flex-direction: column;
+    transition: width 0.35s cubic-bezier(0.4, 0, 0.2, 1);
+    z-index: 1000;
+    position: relative;
+    overflow: hidden;
+    will-change: width;
+    box-sizing: border-box;
+    /* Performance optimization */
+    transform: translateZ(0);
+    backface-visibility: hidden;
+}
+
+:root {
+    --bg-sidebar: #f9f9f9;
+}
+
+.dark {
+    --bg-sidebar: #171717;
+}
+
+/* Removing sidebar-reopen-btn as we now use a slim sidebar state */
+
+.sidebar-container.closed {
+    width: 60px;
+    /* Slimmer width as requested */
+    transform: none;
+    opacity: 1;
+}
+
+/* Restored original smooth transition for all text-like elements */
+.nav-item span,
+.nav-item-pill span,
+.brand-name,
+.profile-info,
+.profile-name,
+.profile-plan,
+.chat-item-text,
+.chat-item-text span,
+.chat-pin-icon,
+.history-label span,
+.history-label svg,
+.upgrade-btn {
+    transition: opacity 0.35s cubic-bezier(0.4, 0, 0.2, 1), transform 0.35s cubic-bezier(0.4, 0, 0.2, 1);
+    white-space: nowrap;
+    opacity: 1;
+}
+
+/* Transitions for elements with dynamic opacity (active/hover) */
+.active-indicator,
+.chat-item-actions {
+    transition: opacity 0.35s cubic-bezier(0.4, 0, 0.2, 1), transform 0.35s cubic-bezier(0.4, 0, 0.2, 1);
+}
+
+/* Final Unified Alignment: 68px (bar) - 20px (margins) = 48px inner. Center = 24px. Icon 32px? wait. 
+   Margin: 10px left. Padding-left: 8px. Total 18px left. Icon 32px. 
+   18 + 32 = 50px right edge of icon. 
+   68 width. 18px remaining on right. 
+   So 18px Left space, 18px Right space. Perfect center!
+*/
+/* Unified constant geometry for open/closed states */
+.sidebar-container.closed .sidebar-brand,
+.sidebar-container.closed .nav-item,
+.sidebar-container.closed .nav-item-pill,
+.sidebar-container.closed .profile-section,
+.sidebar-container.closed .collapsed-footer-actions {
+    margin: 2px 8px !important;
+    width: calc(100% - 16px) !important;
+    justify-content: flex-start !important;
+}
+
+.sidebar-container.closed .nav-item,
+.sidebar-container.closed .nav-item-pill {
+    padding-left: 12px !important;
+}
+
+.sidebar-container.closed .sidebar-brand,
+.sidebar-container.closed .profile-section {
+    padding-left: 6px !important;
+}
+
+.sidebar-container.closed .nav-item-icon {
+    margin: 0 !important;
+    width: 20px !important;
+    min-width: 20px !important;
+    height: 20px !important;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    transform: none !important;
+}
+
+.sidebar-container.closed .profile-avatar,
+.sidebar-container.closed .brand-logo {
+    margin: 0 !important;
+    width: 32px !important;
+    min-width: 32px !important;
+    height: 32px !important;
+    transform: none !important;
+    /* Avatar must stay stationary when sidebar closes */
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    transform: none !important;
+}
+
+/* Merged and stabilized icons */
+
+.sidebar-container.closed .brand-name,
+.sidebar-container.closed .nav-item span,
+.sidebar-container.closed .nav-item-pill span,
+.sidebar-container.closed .profile-info,
+.sidebar-container.closed .chat-item-text,
+.sidebar-container.closed .chat-item-text span,
+.sidebar-container.closed .chat-pin-icon,
+.sidebar-container.closed .history-label span,
+.sidebar-container.closed .history-label svg,
+.sidebar-container.closed .upgrade-btn,
+.sidebar-container.closed .profile-name,
+.sidebar-container.closed .profile-plan,
+.sidebar-container.closed .active-indicator,
+.sidebar-container.closed .chat-item-actions {
+    opacity: 0;
+    pointer-events: none;
+    transform: translateX(-15px);
+    transition: opacity 0.35s cubic-bezier(0.4, 0, 0.2, 1), transform 0.35s cubic-bezier(0.4, 0, 0.2, 1);
+}
+
+/* Toggle button: only visible when sidebar is open */
+.toggle-sidebar-trigger {
+    cursor: pointer;
+    color: var(--text-tertiary);
+    transition: background 0.25s ease, color 0.2s ease, box-shadow 0.25s ease, transform 0.2s ease;
+    padding: 10px;
+    border-radius: 12px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    background: transparent;
+    border: 1px solid transparent;
+    position: relative;
+}
+
+.toggle-sidebar-trigger:hover {
+    color: var(--text-primary);
+    background: var(--bg-surface-hover);
+    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.04);
+}
+
+.dark .toggle-sidebar-trigger:hover {
+    background: rgba(255, 255, 255, 0.12);
+    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
+}
+
+.toggle-sidebar-trigger:active {
+    opacity: 0.7;
+    transform: scale(0.96);
+}
+
+.toggle-sidebar-trigger svg {
+    transition: color 0.25s ease;
+}
+
+/* Hide toggle button when sidebar is closed */
+.sidebar-container.closed .toggle-sidebar-trigger {
+    display: none;
+}
+
+/* Handle chat item background independently to avoid double-opacity fade */
+.sidebar-container.closed .sidebar-chat-item {
+    background: transparent !important;
+    pointer-events: none;
+}
+
+.sidebar-container.closed .sidebar-top-nav {
+    padding: 0;
+}
+
+.sidebar-container.closed .nav-header {
+    justify-content: flex-start;
+    padding: 0;
+    position: relative;
+    /* Anchor for absolute toggle button */
+}
+
+/* Clickable area when sidebar is closed - from "Dự án" down to footer (but not including footer) */
+.sidebar-clickable-area {
+    position: absolute;
+    top: 0;
+    left: 0;
+    right: 0;
+    bottom: 0;
+    cursor: pointer;
+    pointer-events: auto;
+    z-index: 1;
+    /* Covers only sidebar-history area, not footer */
+}
+
+/* Hide clickable area when sidebar is open */
+.sidebar-container.open .sidebar-clickable-area {
+    display: none;
+}
+
+/* When sidebar is closed, ensure nav items and header don't block clicks */
+.sidebar-container.closed .nav-header {
+    position: relative;
+    z-index: 10;
+    pointer-events: auto;
+}
+
+.sidebar-container.closed .nav-list {
+    position: relative;
+    z-index: 10;
+    pointer-events: auto;
+}
+
+/* sidebar-history should allow clicks to pass through when closed */
+.sidebar-container.closed .sidebar-history {
+    position: relative;
+    z-index: 6;
+    pointer-events: none;
+    /* Allow clicks to pass through to clickable area */
+}
+
+/* Footer should not be clickable when sidebar is closed */
+.sidebar-container.closed .sidebar-footer {
+    position: relative;
+    z-index: 10;
+    pointer-events: auto;
+    /* Footer keeps its normal functionality */
+}
+
+/* sidebar-history should keep pointer-events: none when closed for fade effect */
+
+/* Logo stays stationary during all transitions */
+.sidebar-brand {
+    transition: opacity 0.2s ease, transform 0.2s ease;
+    transform: none !important;
+    /* Always stationary */
+}
+
+.sidebar-container.closed .sidebar-brand {
+    opacity: 1;
+    transform: none !important;
+    /* Keep stationary and visible by default */
+}
+
+/* Logo always visible when sidebar is closed */
+
+/* Profile avatar stays stationary during all transitions */
+.profile-avatar {
+    transform: none !important;
+    /* Avatar never moves */
+    transition: none !important;
+}
+
+.profile-section {
+    transform: none !important;
+    /* Profile section never moves */
+    transition: background 0.2s ease;
+    /* Only allow background color transitions */
+}
+
+.sidebar-inner {
+    flex: 1;
+    display: flex;
+    flex-direction: column;
+    height: 100%;
+    position: relative;
+}
+
+/* --- Top Navigation --- */
+/* --- Top Navigation --- */
+.sidebar-top-nav {
+    padding: 0;
+    /* Removing padding to prevent jump */
+}
+
+.nav-header {
+    height: 60px;
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    margin-bottom: 0.5rem;
+    padding: 0;
+    /* Removed padding to ensure logo is stationary at 30px center */
+    position: relative;
+    /* Anchor for absolute toggle button when closed */
+}
+
+.sidebar-brand {
+    display: flex;
+    align-items: center;
+    gap: 6px;
+    cursor: pointer;
+    padding-left: 6px;
+    /* Constant anchor */
+    margin: 0 8px;
+    /* Constant margin */
+    height: 40px;
+    /* Enforce height */
+}
+
+.brand-logo {
+    width: 32px !important;
+    height: 32px !important;
+    min-width: 32px !important;
+    min-height: 32px !important;
+    flex: 0 0 32px !important;
+    aspect-ratio: 1 / 1 !important;
+    border-radius: 10px;
+    object-fit: cover;
+    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
+    transform: translateY(-0.5px);
+    /* Optical adjustment to center with text */
+}
+
+.sidebar-brand .brand-name {
+    font-family: 'Outfit', sans-serif;
+    font-weight: 700;
+    font-size: 1.15rem;
+    color: var(--text-primary);
+    letter-spacing: -0.02em;
+    min-width: 0;
+}
+
+.toggle-sidebar-trigger {
+    cursor: pointer;
+    color: var(--text-tertiary);
+    transition: background 0.25s ease, color 0.2s ease, box-shadow 0.25s ease, transform 0.2s ease;
+    padding: 10px;
+    border-radius: 12px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    background: transparent;
+    border: 1px solid transparent;
+    position: relative;
+}
+
+.toggle-sidebar-trigger:hover {
+    color: var(--text-primary);
+    background: var(--bg-surface-hover);
+    /* Standardized hover for distinct area */
+    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.04);
+}
+
+.dark .toggle-sidebar-trigger:hover {
+    background: rgba(255, 255, 255, 0.12);
+    /* Slightly clearer in dark mode */
+    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
+}
+
+.toggle-sidebar-trigger:active {
+    opacity: 0.7;
+    transform: scale(0.96);
+}
+
+.toggle-sidebar-trigger svg {
+    transition: color 0.25s ease;
+}
+
+/* Static hover: no translation or scaling */
+.toggle-sidebar-trigger:hover svg {
+    transform: none;
+}
+
+/* Cleaned up conflicting overrides */
+
+/* Base class for all unified nav items */
+.nav-item,
+.nav-item-pill {
+    display: flex;
+    align-items: center;
+    gap: 0.75rem;
+    padding: 0 12px;
+    /* Constant padding */
+    margin: 2px 8px;
+    /* Constant margin */
+    height: 44px;
+    flex-shrink: 0;
+    border-radius: 10px;
+    overflow: hidden;
+    /* Prevent text wrapping during transition */
+    transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
+    color: #475569;
+    /* Slate 600 for better contrast in light mode */
+    font-size: 0.85rem;
+    font-weight: 600;
+    /* Bolder as requested */
+    width: calc(100% - 16px);
+    /* Constant width logic */
+    text-align: left;
+    background: transparent;
+    border: none;
+    cursor: pointer;
+}
+
+.dark .nav-item,
+.dark .nav-item-pill {
+    color: var(--text-secondary);
+    /* Retain zinc-400 for dark mode */
+}
+
+.nav-item:hover,
+.nav-item-pill:hover:not(.disabled) {
+    background: var(--bg-surface-hover);
+    /* Darker hover for clarity in light mode */
+    color: var(--text-primary);
+}
+
+.dark .nav-item:hover,
+.dark .nav-item-pill:hover:not(.disabled) {
+    background: var(--bg-surface-hover);
+}
+
+.nav-item-pill.disabled {
+    opacity: 0.5;
+    cursor: not-allowed;
+}
+
+.shortcut-hint {
+    margin-left: auto;
+    font-size: 0.75rem;
+    color: var(--text-secondary);
+    background: rgba(var(--bg-canvas-rgb), 0.3);
+    padding: 3px 9px;
+    border-radius: 6px;
+    border: 1px solid var(--border-medium);
+    opacity: 0;
+    transform: translateX(4px);
+    transition: all 0.2s ease;
+    font-weight: 700;
+    letter-spacing: 0.04em;
+    pointer-events: none;
+    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
+    line-height: 1;
+}
+
+.nav-item:hover .shortcut-hint,
+.context-menu button:hover .shortcut-hint {
+    opacity: 1;
+    transform: translateX(0);
+}
+
+.dark .shortcut-hint {
+    background: rgba(255, 255, 255, 0.08);
+    border-color: rgba(255, 255, 255, 0.15);
+    color: var(--text-secondary);
+    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
+}
+
+.dark .nav-item:hover .shortcut-hint,
+.dark .context-menu button:hover .shortcut-hint {
+    color: var(--text-primary);
+    border-color: rgba(255, 255, 255, 0.3);
+    background: rgba(255, 255, 255, 0.12);
+}
+
+/* Specific icon colors for unified nav items */
+.nav-item .nav-item-icon,
+.nav-item-pill .nav-item-icon {
+    color: #64748b;
+    /* Slate 500 for better contrast in light mode */
+}
+
+.dark .nav-item .nav-item-icon,
+.dark .nav-item-pill .nav-item-icon {
+    color: var(--text-tertiary);
+}
+
+.nav-item:hover .nav-item-icon,
+.nav-item-pill:hover:not(.disabled) .nav-item-icon {
+    color: var(--brand-primary, #6366f1);
+}
+
+.dark .nav-item:hover .nav-item-icon,
+.dark .nav-item-pill:hover:not(.disabled) .nav-item-icon {
+    color: var(--brand-primary, #818cf8);
+}
+
+.nav-item-icon {
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    width: 20px;
+    transition: transform 0.2s;
+}
+
+/* Unified hover icon behavior */
+.nav-item:hover .nav-item-icon,
+.nav-item-pill:hover .nav-item-icon {
+    color: var(--brand-primary, #6366f1);
+}
+
+.nav-item:active {
+    transform: scale(0.98);
+}
+
+.badge-new {
+    font-size: 0.65rem;
+    background: rgba(99, 102, 241, 0.1);
+    color: #6366f1;
+    padding: 2px 8px;
+    border-radius: 999px;
+    margin-left: auto;
+    font-weight: 700;
+    letter-spacing: 0.02em;
+}
+
+/* Removed search-btn overrides to maintain consistency across all nav items */
+
+.dark .badge-new {
+    background: rgba(99, 102, 241, 0.2);
+    color: #818cf8;
+}
+
+/* --- Chat History --- */
+.sidebar-history {
+    flex: 1;
+    display: flex;
+    flex-direction: column;
+    overflow: hidden;
+    margin-top: 1rem;
+    position: relative;
+    margin-left: 8px;
+    /* Added margin to show tour borders on the left */
+}
+
+/* Removed global opacity to allow individual fading */
+.sidebar-container.closed .sidebar-history {
+    pointer-events: none;
+}
+
+.sidebar-container.closed .history-scroll-area {
+    overflow: hidden;
+}
+
+.history-label {
+    padding: 0 1rem 0.5rem;
+    /* Balanced with 8px margin */
+    font-size: 0.75rem;
+    font-weight: 600;
+    color: var(--text-tertiary);
+    text-transform: none;
+}
+
+.history-scroll-area {
+    flex: 1;
+    overflow-y: auto;
+    padding: 0 0.75rem 1rem;
+}
+
+.history-section {
+    display: flex;
+    flex-direction: column;
+    gap: 2px;
+}
+
+.history-empty {
+    padding: 2rem 1rem;
+    /* Balanced with 8px margin */
+    text-align: center;
+    color: var(--text-tertiary);
+    font-size: 0.85rem;
+    font-style: italic;
+}
+
+
+/* --- Profile Footer --- */
+.sidebar-footer {
+    padding: 0.5rem 0 1.25rem;
+    /* Lowered the divider line by reducing top padding */
+    border-top: 1px solid var(--border-light);
+    background: var(--bg-sidebar);
+    transition: transform 0.35s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.35s cubic-bezier(0.4, 0, 0.2, 1), padding 0.35s cubic-bezier(0.4, 0, 0.2, 1);
+    /* Exclude color/background/border from transition to prevent flickering on theme switch */
+    display: flex;
+    flex-direction: column-reverse;
+    /* Pin the 1st DOM child (Profile) to absolute bottom */
+    gap: 0;
+    /* Gap managed by margins of children to avoid jumping */
+}
+
+.sidebar-container.closed .sidebar-footer {
+    padding: 0.75rem 0;
+    gap: 0;
+}
+
+.collapsed-footer-actions {
+    display: flex;
+    flex-direction: column;
+    padding-bottom: 8px;
+    /* Constant spacing from avatar below */
+    transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
+    max-height: 100px;
+    opacity: 1;
+    overflow: hidden;
+}
+
+.sidebar-container.open .collapsed-footer-actions {
+    max-height: 0;
+    opacity: 0;
+    margin: 0;
+    pointer-events: none;
+}
+
+.footer-icon-btn {
+    width: 24px !important;
+    height: 24px !important;
+    min-width: 24px !important;
+    flex: 0 0 24px !important;
+    padding-left: 10px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    border-radius: 8px;
+    color: var(--text-tertiary);
+    background: transparent;
+    border: none;
+    cursor: pointer;
+    transition: opacity 0.35s cubic-bezier(0.4, 0, 0.2, 1), transform 0.35s cubic-bezier(0.4, 0, 0.2, 1), background 0.2s, color 0.2s;
+    opacity: 1;
+}
+
+.sidebar-container.open .footer-icon-btn {
+    width: 40px;
+    height: 40px;
+    border-radius: 12px;
+}
+
+/* Center icon when sidebar is closed and fade it out */
+.sidebar-container.closed .footer-icon-btn {
+    padding-left: 0 !important;
+    margin: 0 auto;
+    opacity: 0;
+    pointer-events: none;
+    transform: translateX(-15px);
+}
+
+.footer-icon-btn:hover {
+    background: var(--bg-surface-hover);
+    color: var(--text-primary);
+}
+
+.profile-section {
+    display: flex;
+    align-items: center;
+    gap: 12px;
+    /* Increased gap for balanced spacing */
+    padding: 0 0 0 6px;
+    /* Vertical padding removed, using fixed height */
+    margin: 0 8px;
+    width: calc(100% - 16px);
+    height: 52px !important;
+    /* Strictly fixed height */
+    min-height: 52px !important;
+    max-height: 52px !important;
+    border-radius: 0.75rem;
+    cursor: pointer;
+    transition: background 0.2s ease;
+    /* Only background transitions, no transform */
+    overflow: hidden;
+    flex-shrink: 0;
+    transform: none !important;
+    /* Profile section never moves */
+}
+
+/* Merged with base profile-section rules and unified alignment */
+
+.profile-section:hover {
+    background: var(--bg-surface-hover);
+}
+
+.profile-avatar {
+    width: 32px !important;
+    height: 32px !important;
+    min-width: 32px !important;
+    min-height: 32px !important;
+    max-width: 32px !important;
+    max-height: 32px !important;
+    flex: 0 0 32px !important;
+    aspect-ratio: 1 / 1 !important;
+    flex-shrink: 0 !important;
+    border-radius: 50%;
+    overflow: hidden;
+    background: var(--bg-surface);
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    transform: none !important;
+    /* Avatar never moves - keep stationary */
+    transition: none !important;
+    /* No transitions on avatar */
+    backface-visibility: hidden;
+}
+
+.avatar-circle {
+    width: 32px;
+    height: 32px;
+    border-radius: 50%;
+    background: #7c3aed;
+    /* Example purple */
+    color: white;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    font-size: 0.875rem;
+    font-weight: 700;
+}
+
+.avatar-circle.small {
+    width: 100%;
+    height: 100%;
+    font-size: 0.9rem;
+    border-radius: 50%;
+}
+
+.profile-info {
+    flex: 1;
+    min-width: 0;
+}
+
+.profile-name {
+    font-size: 0.875rem;
+    font-weight: 700;
+    /* Bolder for prominence */
+    color: var(--text-primary);
+    white-space: nowrap;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    line-height: 1.2;
+}
+
+.profile-plan {
+    font-size: 0.75rem;
+    font-weight: 500;
+    color: var(--text-tertiary);
+    opacity: 0.8;
+}
+
+.upgrade-btn {
+    font-size: 0.75rem;
+    font-weight: 600;
+    padding: 4px 10px;
+    border-radius: 12px;
+    border: 1px solid var(--border-light);
+    background: var(--bg-surface);
+    color: var(--text-primary);
+    transition: transform 0.2s, opacity 0.2s, box-shadow 0.2s;
+    /* Exclude color/background/border from transition to prevent flickering on theme switch */
+    flex-shrink: 0;
+}
+
+.upgrade-btn:hover {
+    background: var(--text-primary);
+    color: var(--bg-surface);
+    border-color: var(--text-primary);
+}
+
+/* Modal centered */
+.modal-overlay.centered {
+    position: fixed;
+    inset: 0;
+    z-index: 2000;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    background: rgba(0, 0, 0, 0.4);
+    backdrop-filter: blur(8px);
+    padding: 1.5rem;
+    animation: fadeIn 0.3s ease-out;
+}
+
+.glass {
+    background: var(--bg-modal);
+    backdrop-filter: blur(32px);
+    -webkit-backdrop-filter: blur(32px);
+    border: 1px solid var(--border-light);
+    box-shadow: 0 24px 64px rgba(0, 0, 0, 0.3);
+}
+
+/* Skip entrance animations when restoring after page refresh */
+.no-animation {
+    animation: none !important;
+}
+
+.no-animation .settings-container,
+.no-animation .search-modal-container {
+    animation: none !important;
+}
+
+.settings-container.no-animation,
+.search-modal-container.no-animation {
+    animation: none !important;
+}
+
+/* --- Settings Modal Redesign --- */
+.settings-container {
+    width: 100%;
+    max-width: 820px;
+    height: 640px;
+    max-height: 90vh;
+    display: flex;
+    border-radius: 24px;
+    overflow: hidden;
+    animation: scaleIn 0.3s cubic-bezier(0.16, 1, 0.3, 1);
+    position: relative;
+}
+
+.settings-nav {
+    width: 240px;
+    background: #f1f5f9;
+    /* Solid subtle gray for better contrast */
+    border-right: 1px solid var(--border-light);
+    display: flex;
+    flex-direction: column;
+    padding: 1.5rem 1rem;
+}
+
+.dark .settings-nav {
+    background: #111113;
+    /* Darker sidebar for prominence */
+}
+
+.nav-title {
+    font-size: 1.25rem;
+    font-weight: 800;
+    margin-bottom: 2rem;
+    padding-left: 0.5rem;
+    color: var(--text-primary);
+}
+
+.nav-items {
+    display: flex;
+    flex-direction: column;
+    gap: 0.5rem;
+}
+
+.nav-tab {
+    display: flex;
+    align-items: center;
+    gap: 0.75rem;
+    padding: 0.85rem 1rem;
+    border-radius: 14px;
+    font-size: 0.95rem;
+    font-weight: 600;
+    color: var(--text-secondary);
+    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
+    background: transparent;
+    border: none;
+    /* Explicitly reset any inherited borders */
+    outline: none;
+    text-align: left;
+    cursor: pointer;
+}
+
+.nav-tab:hover {
+    background: var(--bg-surface-hover);
+    color: var(--text-primary);
+}
+
+.nav-tab.active {
+    background: var(--brand-primary);
+    color: white !important;
+    box-shadow: 0 4px 15px rgba(var(--brand-primary-rgb), 0.3);
+}
+
+.dark .nav-tab.active {
+    background: #3b82f6;
+    /* Azure Blue for vibrant active state */
+    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.4);
+}
+
+.settings-body {
+    flex: 1;
+    display: flex;
+    flex-direction: column;
+    background: var(--bg-modal);
+    position: relative;
+    padding: 2.5rem;
+}
+
+.body-close {
+    all: unset;
+    position: absolute;
+    top: 0.75rem;
+    right: 0.75rem;
+    width: 36px;
+    height: 36px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    border-radius: 50%;
+    color: var(--text-tertiary);
+    cursor: pointer;
+    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
+    z-index: 1000;
+}
+
+.body-close:hover {
+    background: var(--bg-surface-hover);
+    color: #ef4444;
+    transform: rotate(90deg);
+}
+
+.dark .body-close:hover {
+    background: rgba(255, 255, 255, 0.1);
+}
+
+.body-content {
+    flex: 1;
+    overflow-y: auto;
+    padding-right: 0.5rem;
+    scrollbar-width: none;
+    /* Firefox */
+    -ms-overflow-style: none;
+    /* IE/Edge */
+}
+
+.body-content::-webkit-scrollbar {
+    display: none;
+}
+
+.content-header h2 {
+    font-size: 1.75rem;
+    font-weight: 800;
+    margin-bottom: 2rem;
+    color: var(--text-primary);
+}
+
+.content-section {
+    animation: fadeInSlideUp 0.4s ease-out;
+}
+
+/* --- General Groups --- */
+.setting-group {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    padding: 1.25rem 0.5rem;
+    border-bottom: 1px solid var(--border-light);
+    transition: background 0.2s;
+}
+
+.setting-group:hover {
+    background: rgba(var(--brand-primary-rgb), 0.02);
+}
+
+.group-info h3 {
+    font-size: 0.95rem;
+    font-weight: 700;
+    margin-bottom: 0.2rem;
+    color: var(--text-primary);
+}
+
+.group-info p {
+    font-size: 0.82rem;
+    color: var(--text-secondary);
+    line-height: 1.5;
+}
+
+.toggle-pill {
+    padding: 6px 18px;
+    border-radius: 30px;
+    font-size: 0.75rem;
+    font-weight: 700;
+    cursor: pointer;
+    border: 1.5px solid var(--border-light);
+    background: transparent;
+    color: var(--text-secondary);
+    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
+    outline: none !important;
+    box-shadow: none !important;
+}
+
+.toggle-pill.on {
+    background: #3b82f6;
+    border-color: #3b82f6;
+    color: white;
+    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.2) !important;
+}
+
+.toggle-pill.on:hover {
+    background: #2563eb;
+    border-color: #2563eb;
+    transform: translateY(-1px);
+    box-shadow: 0 6px 16px rgba(59, 130, 246, 0.3) !important;
+}
+
+.toggle-pill:not(.on):hover {
+    border-color: #3b82f6;
+    color: #3b82f6;
+    background: rgba(59, 130, 246, 0.05);
+}
+
+/* --- User Profile Card --- */
+.user-profile-card {
+    display: flex;
+    align-items: center;
+    gap: 1.5rem;
+    padding: 1.5rem;
+    background: var(--bg-surface);
+    border: 1px solid var(--border-light);
+    border-radius: 20px;
+    margin-bottom: 2rem;
+    transition: all 0.3s ease;
+}
+
+.user-profile-card.editing {
+    flex-direction: column;
+    align-items: center;
+    padding: 2.5rem 2rem;
+    gap: 2rem;
+    text-align: center;
+}
+
+.user-profile-card:hover {
+    border-color: rgba(var(--brand-primary-rgb), 0.3);
+    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.03);
+}
+
+.dark .user-profile-card {
+    background: rgba(255, 255, 255, 0.02);
+}
+
+.card-avatar {
+    position: relative;
+    width: 64px;
+    height: 64px;
+}
+
+.card-avatar.large {
+    width: 110px;
+    height: 110px;
+    margin-bottom: 0.5rem;
+}
+
+.avatar-placeholder {
+    width: 100%;
+    height: 100%;
+    border-radius: 50%;
+    background: linear-gradient(135deg, #7c3aed, #3b82f6);
+    color: white;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    font-size: 1.5rem;
+    font-weight: 800;
+}
+
+.avatar-placeholder.large {
+    font-size: 3rem;
+}
+
+.card-avatar img {
+    width: 100%;
+    height: 100%;
+    border-radius: 50%;
+    object-fit: cover;
+    border: 3px solid var(--bg-modal);
+    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
+}
+
+.avatar-edit-overlay {
+    position: absolute;
+    inset: 0;
+    background: rgba(0, 0, 0, 0.4);
+    backdrop-filter: blur(4px);
+    border-radius: 50%;
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    color: white;
+    cursor: pointer;
+    opacity: 0;
+    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
+    font-size: 0.75rem;
+    font-weight: 700;
+    gap: 4px;
+    border: 2px solid transparent;
+}
+
+.card-avatar:hover .avatar-edit-overlay {
+    opacity: 1;
+}
+
+.card-form {
+    width: 100%;
+    display: flex;
+    flex-direction: column;
+    gap: 1.5rem;
+    text-align: left;
+}
+
+.form-group {
+    display: flex;
+    flex-direction: column;
+    gap: 0.6rem;
+}
+
+.form-group label {
+    font-size: 0.75rem;
+    font-weight: 800;
+    color: var(--text-tertiary);
+    text-transform: uppercase;
+    letter-spacing: 0.08em;
+    padding-left: 0.25rem;
+}
+
+.form-group input {
+    padding: 0.85rem 1.1rem;
+    background: var(--bg-canvas);
+    border: 1.5px solid var(--border-light);
+    border-radius: 14px;
+    color: var(--text-primary);
+    font-size: 0.95rem;
+    transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
+}
+
+.form-group input:focus {
+    outline: none;
+    border-color: #3b82f6;
+    background: var(--bg-surface);
+    box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.15);
+}
+
+.save-profile-btn {
+    margin-top: 0.75rem;
+    padding: 0.9rem;
+    background: #3b82f6;
+    color: white;
+    border: none;
+    border-radius: 14px;
+    font-weight: 700;
+    font-size: 0.95rem;
+    cursor: pointer;
+    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
+    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.2);
+}
+
+.save-profile-btn:hover:not(:disabled) {
+    background: #2563eb;
+    filter: brightness(1.1);
+    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.3);
+}
+
+.save-profile-btn:active:not(:disabled) {
+    transform: scale(0.98);
+}
+
+.save-profile-btn:disabled {
+    opacity: 0.4;
+    cursor: not-allowed;
+    background: var(--text-tertiary);
+    box-shadow: none;
+}
+
+.account-danger-zone {
+    border-top: 1px solid var(--border-light);
+    padding-top: 2rem;
+    margin-top: 1rem;
+    width: 100%;
+}
+
+/* --- Appearance Grid --- */
+.appearance-grid {
+    display: grid;
+    grid-template-columns: repeat(2, 1fr);
+    gap: 1.5rem;
+}
+
+.theme-card {
+    display: flex;
+    flex-direction: column;
+    gap: 1rem;
+    padding: 1.25rem;
+    border-radius: 20px;
+    border: 2.5px solid transparent;
+    background: var(--bg-surface);
+    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
+    text-align: left;
+    cursor: pointer;
+}
+
+.theme-card:hover {
+    background: var(--bg-surface-hover);
+    transform: translateY(-2px);
+}
+
+.theme-card.active {
+    border-color: var(--brand-primary);
+    background: var(--bg-canvas);
+    box-shadow: 0 8px 24px rgba(var(--brand-primary-rgb), 0.15);
+}
+
+.sidebar-avatar-img {
+    width: 32px !important;
+    height: 32px !important;
+    min-width: 32px !important;
+    min-height: 32px !important;
+    max-width: 32px !important;
+    max-height: 32px !important;
+    aspect-ratio: 1 / 1 !important;
+    object-fit: cover;
+    border-radius: 50%;
+    flex-shrink: 0 !important;
+}
+
+.theme-card span {
+    font-size: 0.95rem;
+    font-weight: 700;
+    color: var(--text-primary);
+    /* Ensure contrast */
+}
+
+.theme-preview {
+    height: 100px;
+    border-radius: 12px;
+}
+
+.theme-preview.light {
+    background: #ffffff;
+    border: 1px solid #e2e8f0;
+}
+
+.theme-preview.dark {
+    background: #18181b;
+    border: 1px solid #27272a;
+}
+
+
+/* --- Archived List --- */
+.archived-list {
+    display: flex;
+    flex-direction: column;
+    gap: 0.75rem;
+}
+
+.archived-row {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    padding: 0.85rem 1.25rem;
+    background: var(--bg-surface);
+    border: 1px solid var(--border-light);
+    border-radius: 12px;
+    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
+}
+
+.archived-row:hover {
+    background: var(--bg-surface-hover);
+    border-color: rgba(var(--brand-primary-rgb), 0.3);
+    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
+}
+
+.row-info {
+    display: flex;
+    flex-direction: column;
+    gap: 0.15rem;
+}
+
+.row-title {
+    font-size: 0.95rem;
+    font-weight: 600;
+    color: var(--text-primary);
+}
+
+.row-date {
+    font-size: 0.75rem;
+    color: var(--text-tertiary);
+    font-weight: 500;
+}
+
+.restore-btn {
+    display: flex;
+    align-items: center;
+    gap: 0.4rem;
+    padding: 5px 12px;
+    border-radius: 10px;
+    font-size: 0.8rem;
+    font-weight: 600;
+    color: #3b82f6;
+    background: rgba(59, 130, 246, 0.05);
+    border: 1.5px solid rgba(59, 130, 246, 0.1);
+    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
+    cursor: pointer;
+}
+
+.restore-btn:hover {
+    background: #3b82f6;
+    color: white;
+    border-color: #3b82f6;
+    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.2);
+}
+
+.dark .restore-btn {
+    background: rgba(59, 130, 246, 0.15);
+    border-color: rgba(59, 130, 246, 0.2);
+}
+
+.dark .restore-btn:hover {
+    background: #3b82f6;
+    border-color: #3b82f6;
+}
+
+/* --- Utility --- */
+.danger-btn-outline {
+    width: 100%;
+    padding: 0.85rem;
+    border: 2px solid #ef4444;
+    background: transparent;
+    color: #ef4444;
+    border-radius: 16px;
+    font-weight: 700;
+    font-size: 0.9rem;
+    letter-spacing: 0.01em;
+    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
+    cursor: pointer;
+    position: relative;
+    overflow: hidden;
+}
+
+.danger-btn-outline:hover {
+    background: rgba(239, 68, 68, 0.1);
+    box-shadow: 0 0 15px rgba(239, 68, 68, 0.2);
+    border-color: #f87171;
+}
+
+.danger-btn-outline:active {
+    background: rgba(239, 68, 68, 0.15);
+    transform: scale(0.985);
+}
+
+.danger-text {
+    display: block;
+    width: fit-content;
+    background: none;
+    border: none;
+    color: #ef4444;
+    font-weight: 600;
+    font-size: 0.85rem;
+    cursor: pointer;
+    padding: 0.5rem 1rem;
+    margin-top: 1.5rem;
+    border-radius: 8px;
+    opacity: 0.6;
+    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
+}
+
+.danger-text:hover {
+    opacity: 1;
+    background: rgba(239, 68, 68, 0.05);
+    color: #f87171;
+}
+
+
+.mt-8 {
+    margin-top: 2rem;
+}
+
+.mt-4 {
+    margin-top: 1rem;
+}
+
+.mb-4 {
+    margin-bottom: 1rem;
+}
+
+@keyframes scaleIn {
+    from {
+        opacity: 0;
+        transform: scale(0.9);
+    }
+
+    to {
+        opacity: 1;
+        transform: scale(1);
+    }
+}
+
+/* Search Modal Centered */
+.search-modal-container {
+    width: 95%;
+    max-width: 600px;
+    height: 520px;
+    /* ABSOLUTELY FIXED - No jumping ever */
+    border-radius: 1.25rem;
+    overflow: hidden;
+    display: flex;
+    flex-direction: column;
+    box-shadow: 0 50px 100px -20px rgba(0, 0, 0, 0.15), 0 30px 60px -30px rgba(0, 0, 0, 0.2);
+    border: 1px solid var(--border-medium);
+    animation: zoomIn 0.3s cubic-bezier(0.16, 1, 0.3, 1);
+    background: var(--bg-modal);
+    backdrop-filter: blur(28px) saturate(180%);
+}
+
+.dark .search-modal-container {
+    background: rgba(15, 15, 18, 0.98);
+    border-color: rgba(255, 255, 255, 0.12);
+    box-shadow: 0 40px 80px -20px rgba(0, 0, 0, 0.8);
+}
+
+.search-modal-header {
+    height: 72px;
+    /* Increased height for better balance */
+    padding: 0 1.5rem;
+    display: flex;
+    align-items: center;
+    gap: 1rem;
+    background: rgba(var(--bg-canvas-rgb), 0.6);
+    /* More opaque for "fixed" feel */
+    border-bottom: 1px solid var(--border-light);
+    transition: all 0.3s ease;
+    flex-shrink: 0;
+}
+
+.search-modal-header:focus-within {
+    background: rgba(var(--bg-canvas-rgb), 0.7);
+    border-bottom-color: var(--brand-primary);
+}
+
+.search-input {
+    flex: 1;
+    background: transparent;
+    border: none;
+    outline: none;
+    font-size: 1.15rem;
+    /* Larger font for readability */
+    color: var(--text-primary);
+    font-family: 'Outfit', sans-serif;
+    letter-spacing: -0.01em;
+    padding: 0.5rem 0;
+}
+
+.search-input::placeholder {
+    color: var(--text-tertiary);
+    opacity: 0.7;
+}
+
+.dark .search-input::placeholder {
+    color: var(--text-secondary);
+    opacity: 0.5;
+}
+
+.search-shortcut {
+    font-size: 0.6rem;
+    background: var(--bg-surface-hover);
+    color: var(--text-secondary);
+    padding: 4px 8px;
+    /* Better padding */
+    border-radius: 6px;
+    font-weight: 800;
+    border: 1px solid var(--border-medium);
+    opacity: 0.8;
+    letter-spacing: 0.05em;
+    font-family: 'Inter', sans-serif;
+}
+
+.dark .search-shortcut {
+    background: rgba(255, 255, 255, 0.1);
+    color: var(--text-secondary);
+    border-color: rgba(255, 255, 255, 0.15);
+}
+
+.search-modal-content {
+    flex: 1;
+    overflow-y: auto;
+    padding: 0.75rem;
+    display: flex;
+    /* Centering empty state */
+    flex-direction: column;
+}
+
+.search-modal-content>div {
+    flex: 1;
+    display: flex;
+    flex-direction: column;
+}
+
+.search-group {
+    margin-bottom: 1.5rem;
+}
+
+.search-group:last-child {
+    margin-bottom: 0.5rem;
+}
+
+.group-title {
+    padding: 0 0.75rem;
+    margin-bottom: 0.75rem;
+    font-size: 0.7rem;
+    font-weight: 800;
+    color: var(--text-tertiary);
+    text-transform: uppercase;
+    letter-spacing: 0.1em;
+}
+
+.group-items {
+    display: flex;
+    flex-direction: column;
+    gap: 2px;
+}
+
+.search-result-item {
+    display: flex;
+    align-items: center;
+    gap: 0.875rem;
+    padding: 0.75rem 0.875rem;
+    border-radius: 0.75rem;
+    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
+    width: 100%;
+    text-align: left;
+    background: transparent;
+    border: none;
+    cursor: pointer;
+}
+
+.search-result-item:hover {
+    background: var(--bg-surface-hover);
+}
+
+.dark .search-result-item:hover {
+    background: rgba(255, 255, 255, 0.06);
+}
+
+.search-result-item:hover .item-icon {
+    background: var(--bg-canvas);
+    color: var(--brand-primary);
+}
+
+.item-icon {
+    width: 32px;
+    height: 32px;
+    background: var(--bg-surface-hover);
+    border-radius: 8px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    color: var(--text-secondary);
+    transition: all 0.2s ease;
+    flex-shrink: 0;
+}
+
+.dark .item-icon {
+    background: rgba(255, 255, 255, 0.05);
+    color: var(--text-secondary);
+}
+
+.item-title {
+    font-size: 0.95rem;
+    font-weight: 500;
+    color: var(--text-primary);
+    transition: color 0.2s ease;
+}
+
+.empty-state {
+    flex: 1;
+    /* Occupy remaining space */
+    padding: 2rem 1rem;
+    text-align: center;
+    color: var(--text-secondary);
+    font-size: 0.9rem;
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    /* Center vertically */
+    gap: 1.5rem;
+    opacity: 0.9;
+}
+
+.dark .empty-state {
+    color: var(--text-secondary);
+    opacity: 0.8;
+}
+
+@keyframes zoomIn {
+    from {
+        opacity: 0;
+        transform: scale(0.95);
+    }
+
+    to {
+        opacity: 1;
+        transform: scale(1);
+    }
+}
+
+@keyframes fadeInSlideUp {
+    from {
+        opacity: 0;
+        transform: translateY(10px);
+    }
+
+    to {
+        opacity: 1;
+        transform: translateY(0);
+    }
+}
+
+/* Search result snippet & metadata */
+.item-title b,
+.search-result-item .bg-brand-primary\/20 {
+    background: rgba(var(--brand-primary-rgb), 0.15);
+    color: var(--brand-primary);
+    padding: 1px 4px;
+    /* Slightly better surrounding space */
+    border-radius: 4px;
+    font-weight: 700;
+    /* Bolder for visibility */
+    box-shadow: 0 0 0 1px rgba(var(--brand-primary-rgb), 0.1);
+    /* Subtle outline for depth */
+}
+
+.dark .item-title b,
+.dark .search-result-item .bg-brand-primary\/20 {
+    background: rgba(var(--brand-primary-rgb), 0.25);
+    color: #a5b4fc;
+    /* Indigo 300 for better pop */
+    box-shadow: 0 0 0 1px rgba(var(--brand-primary-rgb), 0.2);
+}
+
+.search-result-item p {
+    color: var(--text-secondary);
+    /* Softer for better hierarchy */
+    font-size: 0.825rem;
+    line-height: 1.5;
+    margin-top: 4px;
+    display: -webkit-box;
+    -webkit-line-clamp: 2;
+    /* Increased to 2 lines for better context */
+    -webkit-box-orient: vertical;
+    overflow: hidden;
+}
+
+.dark .search-result-item p {
+    color: var(--text-secondary);
+    opacity: 0.7;
+}
+
+.dark .search-result-item .item-title {
+    color: var(--text-primary) !important;
+}
+
+.search-result-item .item-date {
+    font-size: 0.65rem;
+    font-weight: 700;
+    color: var(--text-secondary);
+    opacity: 0.6;
+    letter-spacing: 0.05em;
+    transition: opacity 0.2s ease;
+}
+
+.search-result-item:hover .item-date {
+    opacity: 1;
+}
+
+.dark .search-result-item .item-date {
+    color: var(--text-secondary);
+    opacity: 0.5;
+}
+
+.dark .search-result-item:hover .item-date {
+    color: var(--text-primary);
+    opacity: 0.8;
+}
+
+/* Attachment Menu */
+.attachment-menu {
+    position: absolute;
+    bottom: 100%;
+    left: 0;
+    margin-bottom: 0.5rem;
+    background: var(--bg-modal);
+    backdrop-filter: blur(12px);
+    border: 1px solid var(--border-light);
+    border-radius: 0.75rem;
+    box-shadow: var(--shadow-lg);
+    padding: 0.5rem;
+    min-width: 180px;
+    z-index: 100;
+    animation: fadeIn 0.15s ease-out;
+}
+
+.attachment-menu button {
+    width: 100%;
+    display: flex;
+    align-items: center;
+    gap: 0.75rem;
+    padding: 0.6rem 0.75rem;
+    background: none;
+    border: none;
+    cursor: pointer;
+    font-size: 0.875rem;
+    color: var(--text-primary);
+    border-radius: 0.5rem;
+}
+
+.attachment-menu button:hover {
+    background: var(--bg-surface-hover);
+}
+
+/* Search Modal */
+.modal-overlay {
+    background: rgba(0, 0, 0, 0.6);
+    backdrop-filter: blur(4px);
+}
+
+.search-modal {
+    background: var(--bg-canvas);
+    border: 1px solid var(--border-light);
+    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
+    border-radius: 1rem;
+}
+
+.search-header {
+    border-bottom: 1px solid var(--border-light);
+    background: var(--bg-surface);
+}
+
+.search-results {
+    background: var(--bg-canvas);
+}
+
+.search-item {
+    color: var(--text-primary);
+}
+
+.search-item:hover {
+    background: var(--bg-surface-hover);
+}
+
+/* Scroll to bottom */
+.scroll-to-bottom {
+    position: absolute;
+    left: 50%;
+    transform: translateX(-50%);
+    bottom: 1.5rem;
+    /* Lowered, right above input area */
+    width: 36px;
+    /* Slightly smaller to be less intrusive */
+    height: 36px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    border-radius: 50%;
+    z-index: 40;
+    background: rgba(var(--bg-surface-rgb, 255, 255, 255), 0.6);
+    /* Transparent background */
+    backdrop-filter: blur(8px);
+    /* Glassmorphism effect */
+    -webkit-backdrop-filter: blur(8px);
+    border: 1px solid var(--border-light);
+    color: var(--text-secondary);
+    box-shadow: var(--shadow-sm);
+    cursor: pointer;
+    transition: transform 0.2s cubic-bezier(0.4, 0, 0.2, 1), box-shadow 0.2s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.2s cubic-bezier(0.4, 0, 0.2, 1);
+    opacity: 0.7;
+    /* Initially semi-transparent */
+}
+
+.scroll-to-bottom:hover {
+    background: rgba(var(--bg-surface-rgb, 255, 255, 255), 0.8);
+    color: var(--brand-primary);
+    opacity: 1;
+    transform: translateX(-50%) translateY(-2px);
+    box-shadow: var(--shadow-md);
+}
+
+/* Pin Indicator Icon */
+.chat-pin-icon {
+    display: inline-block;
+    vertical-align: middle;
+    margin-right: 8px;
+    color: #3b82f6;
+    flex-shrink: 0;
+}
+
+/* Premium Toast Notification */
+.premium-toast {
+    position: fixed;
+    bottom: 2rem;
+    left: 50%;
+    transform: translateX(-50%);
+    background: #ffffff;
+    padding: 12px 20px;
+    border-radius: 12px;
+    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.1), 0 5px 15px rgba(0, 0, 0, 0.05);
+    display: flex;
+    align-items: center;
+    gap: 16px;
+    z-index: 9999;
+    border: 1px solid rgba(0, 0, 0, 0.05);
+    animation: toastSlideUp 0.4s cubic-bezier(0.16, 1, 0.3, 1);
+}
+
+.dark .premium-toast {
+    background: #1e1e1e;
+    border-color: rgba(255, 255, 255, 0.1);
+    color: #ffffff;
+}
+
+.premium-toast.warning {
+    border-left: 4px solid #f59e0b;
+}
+
+.toast-icon {
+    font-size: 20px;
+}
+
+.toast-content strong {
+    display: block;
+    font-size: 14px;
+    margin-bottom: 2px;
+}
+
+.toast-content p {
+    font-size: 13px;
+    margin: 0;
+    opacity: 0.8;
+}
+
+@keyframes toastSlideUp {
+    from {
+        opacity: 0;
+        transform: translate(-50%, 20px);
+    }
+
+    to {
+        opacity: 1;
+        transform: translate(-50%, 0);
+    }
+}
+
+/* Premium PDF Export Styling */
+.pdf-export-container {
+    padding: 60px 50px;
+    background: white !important;
+    color: #1a1a1a !important;
+    font-family: 'Inter', -apple-system, blinkmacsystemfont, 'Segoe UI', roboto, sans-serif;
+    line-height: 1.6;
+    width: 800px;
+    position: fixed;
+    left: -2000px;
+    top: 0;
+    z-index: 9999;
+}
+
+/* Force dark text for all elements in PDF regardless of app theme */
+.pdf-export-container * {
+    color: #1a1a1a !important;
+}
+
+.pdf-watermark {
+    position: absolute;
+    top: 50%;
+    left: 50%;
+    transform: translate(-50%, -50%) rotate(-45deg);
+    font-size: 120px;
+    font-weight: 900;
+    color: rgba(0, 0, 0, 0.03) !important;
+    /* Extremely subtle */
+    pointer-events: none;
+    z-index: 0;
+    white-space: nowrap;
+}
+
+.pdf-header {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    border-bottom: 2px solid #f0f0f0;
+    margin-bottom: 30px;
+    padding-bottom: 15px;
+}
+
+.pdf-brand {
+    font-size: 24px;
+    font-weight: 800;
+    color: #4f46e5 !important;
+    letter-spacing: -0.02em;
+}
+
+.pdf-meta {
+    text-align: right;
+    font-size: 12px;
+    color: #666 !important;
+}
+
+.pdf-content {
+    font-size: 14px;
+}
+
+.pdf-content h1,
+.pdf-content h2,
+.pdf-content h3 {
+    color: #111;
+    margin-top: 1.5em;
+    margin-bottom: 0.5em;
+}
+
+.pdf-export-container .katex-display {
+    background: transparent;
+    padding: 10px 0;
+    border: none;
+    margin: 20px 0;
+}
+
+.pdf-footer {
+    margin-top: 50px;
+    padding-top: 15px;
+    border-top: 1px solid #f0f0f0;
+    font-size: 10px;
+    color: #999 !important;
+    text-align: center;
+}
+
+/* --- Unsaved Changes Warning --- */
+.unsaved-warning-overlay {
+    position: absolute;
+    inset: 0;
+    z-index: 1000;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    backdrop-filter: blur(12px);
+    background: rgba(0, 0, 0, 0.4);
+    animation: fadeIn 0.3s ease-out;
+    border-radius: 24px;
+}
+
+.warning-content {
+    background: var(--bg-surface);
+    padding: 2.5rem;
+    border-radius: 20px;
+    width: 90%;
+    max-width: 440px;
+    text-align: center;
+    border: 1px solid var(--border-light);
+    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
+    transform: scale(0.95);
+    animation: scaleIn 0.3s cubic-bezier(0.16, 1, 0.3, 1) forwards;
+}
+
+.warning-icon-wrapper {
+    width: 60px;
+    height: 60px;
+    background: rgba(245, 158, 11, 0.1);
+    border-radius: 50%;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    margin: 0 auto 1.5rem;
+}
+
+.warning-content h3 {
+    font-size: 1.35rem;
+    margin-bottom: 0.75rem;
+    color: var(--text-primary);
+}
+
+.warning-content p {
+    font-size: 0.95rem;
+    color: var(--text-secondary);
+    line-height: 1.6;
+    margin-bottom: 2rem;
+}
+
+.warning-actions {
+    display: grid;
+    grid-template-columns: repeat(3, 1fr);
+    gap: 0.75rem;
+}
+
+.warning-btn {
+    padding: 0.75rem;
+    border-radius: 12px;
+    font-size: 0.85rem;
+    font-weight: 600;
+    cursor: pointer;
+    transition: all 0.2s;
+    border: 1px solid transparent;
+}
+
+.warning-btn.discard {
+    background: transparent;
+    border-color: var(--border-light);
+    color: var(--text-secondary);
+}
+
+.warning-btn.discard:hover {
+    background: var(--bg-surface-hover);
+    color: #ef4444;
+}
+
+.warning-btn.cancel {
+    background: var(--bg-surface-hover);
+    color: var(--text-primary);
+}
+
+.warning-btn.cancel:hover {
+    background: var(--bg-surface-active);
+}
+
+.warning-btn.save {
+    background: var(--brand-primary);
+    color: white;
+}
+
+.warning-btn.save:hover {
+    filter: brightness(1.1);
+    box-shadow: 0 4px 12px rgba(124, 58, 237, 0.3);
+}
+
+.save-profile-btn.active {
+    background: var(--brand-primary);
+    color: white;
+    box-shadow: 0 4px 15px rgba(124, 58, 237, 0.3);
+}
+
+.save-profile-btn.active:hover {
+    filter: brightness(1.1);
+}
+
+@keyframes fadeIn {
+    from {
+        opacity: 0;
+    }
+
+    to {
+        opacity: 1;
+    }
+}
+
+@keyframes scaleIn {
+    to {
+        transform: scale(1);
+        opacity: 1;
+    }
+}
+
+/* Sidebar Help Section */
+.sidebar-help {
+    display: flex;
+    align-items: center;
+    gap: 12px;
+    padding: 10px 12px;
+    margin: 8px 12px;
+    border-radius: 12px;
+    cursor: pointer;
+    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
+    color: var(--text-secondary);
+    border: 1px solid transparent;
+}
+
+.sidebar-help:hover {
+    background: var(--bg-surface-hover);
+    color: var(--text-primary);
+    border-color: var(--border-light);
+}
+
+.sidebar-help .help-icon {
+    flex-shrink: 0;
+    transition: transform 0.2s;
+}
+
+.sidebar-help:hover .help-icon {
+    transform: scale(1.1);
+}
+
+.help-text {
+    font-size: 0.9rem;
+    font-weight: 600;
+    white-space: nowrap;
+    opacity: 1;
+    transition: opacity 0.3s, visibility 0.3s;
+}
+
+.sidebar-collapsed .help-text {
+    opacity: 0;
+    visibility: hidden;
+}
+
+.sidebar-collapsed .sidebar-help {
+    justify-content: center;
+    padding: 10px 0;
+    margin: 8px 4px;
+}
\ No newline at end of file