.app {
  display: flex;
  width: 100%;
  height: 100%;
  position: relative;
  background: var(--bg-primary);
  --keyboard-offset: 0px;
}

/* ── Sidebar ── */

.sidebar {
  width: 260px;
  min-width: 260px;
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  contain: layout style paint;
}

.sidebar-header {
  padding: 16px;
}

.sidebar-title-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
}

.sidebar-header h1 {
  font-family: var(--font-serif);
  font-size: 18px;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.settings-btn {
  background: transparent;
  color: var(--text-faint);
  font-size: 16px;
  padding: 4px 6px;
  border-radius: var(--radius-sm);
  transition: background 0.2s ease, color 0.2s ease, transform 0.2s ease;
}

.settings-btn:hover {
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  transform: rotate(20deg);
}

.new-session-btn {
  width: 100%;
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  padding: 9px 12px;
  font-weight: 500;
  font-size: 13px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  cursor: pointer;
  transition: background 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.new-session-btn:hover:not(:disabled) {
  background: var(--bg-hover);
  color: var(--text-primary);
  border-color: var(--accent-border);
}

.new-session-btn:disabled {
  opacity: 0.3;
}

/* ── Settings Panel ── */

.settings-panel {
  border-bottom: 1px solid var(--border-color);
  max-height: 400px;
  overflow-y: auto;
  animation: fadeIn 0.25s ease;
}

.settings-provider-select {
  padding: 10px 14px;
  border-bottom: 1px solid var(--border-color);
}

.provider-dropdown {
  width: 100%;
}

.provider-dropdown .dropdown-trigger {
  width: 100%;
  font-size: 12px;
  font-weight: 500;
}

.provider-dropdown .dropdown-trigger:hover {
  border-color: var(--accent-border);
}

.provider-dropdown .dropdown-list {
  font-size: 12px;
}

.anthropic-setup,
.custom-providers {
  padding: 14px 16px;
}

.anthropic-setup {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.setup-hint {
  font-size: 12px;
  color: var(--text-tertiary);
  margin-bottom: 4px;
}

.api-key-form {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.api-key-form input {
  font-size: 12px;
  padding: 8px 10px;
}

.settings-error {
  font-size: 11px;
  color: #e5534b;
}

.save-key-btn {
  background: var(--accent);
  color: var(--bg-primary);
  font-size: 12px;
  font-weight: 600;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  transition: background 0.2s ease, box-shadow 0.2s ease;
}

.save-key-btn:hover {
  background: var(--accent-hover);
  box-shadow: var(--glow);
}

.api-key-saved {
  display: flex;
  flex-direction: column;
  gap: 8px;
  align-items: center;
  padding: 10px;
  background: var(--accent-subtle);
  border-radius: var(--radius-sm);
  border: 1px solid var(--accent-border);
}

.key-status {
  font-size: 12px;
  color: var(--text-primary);
  margin: 0;
}

.disconnect-btn {
  background: transparent;
  color: var(--text-faint);
  font-size: 11px;
  padding: 4px 8px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  transition: color 0.2s ease, border-color 0.2s ease;
}

.disconnect-btn:hover {
  color: #e5534b;
  border-color: #e5534b;
}

/* ── Auth Mode Toggle ── */

.auth-mode-toggle {
  display: flex;
  gap: 0;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.auth-mode-btn {
  flex: 1;
  padding: 6px 10px;
  background: transparent;
  color: var(--text-faint);
  font-size: 11px;
  font-weight: 600;
  border: none;
  cursor: pointer;
  letter-spacing: 0.03em;
  transition: color 0.2s ease, background 0.2s ease;
}

.auth-mode-btn:first-child {
  border-right: 1px solid var(--border-color);
}

.auth-mode-btn:hover {
  color: var(--text-secondary);
  background: var(--bg-tertiary);
}

.auth-mode-btn.active {
  background: var(--bg-tertiary);
  color: var(--accent);
}

/* ── OAuth Flow ── */

.oauth-flow {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.oauth-btn {
  width: 100%;
}

.oauth-btn:disabled {
  opacity: 0.5;
}

.oauth-code-form {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.oauth-code-form input {
  font-size: 12px;
  padding: 8px 10px;
}

/* ── Vertex AI ADC Status ── */

.vertex-adc-status {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 4px 0;
}

.adc-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}

.adc-dot.found {
  background: #3fb950;
}

.adc-dot.missing {
  background: #e5534b;
}

.adc-dot.unknown {
  background: var(--text-faint);
}

.save-key-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

/* ── Custom Providers ── */

.custom-providers {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.provider-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.provider-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 10px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-sm);
  transition: background 0.2s ease;
}

.provider-item:hover {
  background: var(--bg-hover);
}

.provider-info {
  display: flex;
  flex-direction: column;
  gap: 1px;
  min-width: 0;
}

.provider-name {
  font-size: 13px;
  font-weight: 500;
  color: var(--text-primary);
}

.provider-url {
  font-size: 11px;
  color: var(--text-faint);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.remove-btn {
  background: transparent;
  color: var(--text-faint);
  font-size: 16px;
  padding: 2px 6px;
  flex-shrink: 0;
  cursor: pointer;
  transition: color 0.2s ease;
}

.remove-btn:hover {
  color: #e5534b;
}

.add-provider-form {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding-top: 8px;
  border-top: 1px solid var(--border-subtle);
}

.add-provider-form input {
  font-size: 12px;
  padding: 7px 10px;
}

.add-provider-btn {
  background: var(--bg-hover);
  color: var(--text-primary);
  font-size: 12px;
  font-weight: 500;
  padding: 7px 12px;
  transition: background 0.2s ease, color 0.2s ease;
}

.add-provider-btn:hover {
  background: var(--bg-active);
}

/* ── Model Selector ── */

.model-selector {
  padding: 12px 16px;
  border-top: 1px solid var(--border-color);
}

.model-selector label {
  display: block;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-faint);
  margin-bottom: 6px;
  font-weight: 500;
}

.model-selector select {
  width: 100%;
  padding: 7px 10px;
  font-size: 13px;
}

.model-connect-hint {
  font-size: 11px;
  color: var(--text-faint);
  padding: 10px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-sm);
  text-align: center;
}

.model-connect-hint p {
  margin: 0;
}

.custom-model-input {
  margin-top: 6px;
  font-size: 12px;
  padding: 7px 10px;
  width: 100%;
}

.link-btn {
  background: none;
  color: var(--accent);
  padding: 0;
  font-size: 11px;
  text-decoration: underline;
  transition: color 0.2s ease;
}

.link-btn:hover {
  color: var(--accent-hover);
}

/* ── Session List ── */

.sessions-list {
  flex: 1;
  overflow-y: auto;
  padding: 6px 8px;
}

.session-item {
  width: 100%;
  padding: 10px 12px;
  margin-bottom: 1px;
  background: transparent;
  border: none;
  border-radius: var(--radius-sm);
  text-align: left;
  display: flex;
  flex-direction: column;
  gap: 2px;
  cursor: pointer;
  border-left: 2px solid transparent;
  transition: background 0.2s ease, border-color 0.25s ease;
}

.session-item:hover {
  background: var(--bg-tertiary);
  border-left-color: var(--accent-border);
}

.session-item.active {
  background: var(--bg-tertiary);
  border-left-color: var(--accent);
}

.session-title {
  font-size: 13px;
  font-weight: 400;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.session-item.active .session-title {
  color: var(--accent);
  font-weight: 500;
}

.session-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.session-item .date {
  font-size: 11px;
  color: var(--text-faint);
}

.delete-session-btn {
  background: transparent;
  color: transparent;
  font-size: 14px;
  padding: 0 4px;
  border: none;
  cursor: pointer;
  line-height: 1;
  transition: color 0.2s ease;
}

.session-item:hover .delete-session-btn {
  color: var(--text-faint);
}

.delete-session-btn:hover {
  color: #e5534b !important;
}

.session-item.streaming {
  border-left: 2px solid var(--accent);
}

.streaming-dot {
  display: inline-block;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
  margin-right: 6px;
  animation: pulse 1.5s ease-in-out infinite;
  vertical-align: middle;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.3; }
}

/* ── Buffer Tabs ── */

.buffer-tabs {
  display: flex;
  border-bottom: 1px solid var(--border-color);
  background: var(--bg-secondary);
  flex-shrink: 0;
}

.buffer-tab {
  padding: 8px 20px;
  background: transparent;
  color: var(--text-faint);
  font-size: 12px;
  font-weight: 500;
  border: none;
  cursor: pointer;
  letter-spacing: 0.03em;
  position: relative;
  transition: color 0.2s ease, background 0.2s ease;
}

.buffer-tab:hover {
  color: var(--text-secondary);
  background: var(--bg-tertiary);
}

.buffer-tab.active {
  color: var(--accent);
}

.buffer-tab.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 15%;
  right: 15%;
  height: 2px;
  background: var(--accent);
  border-radius: 1px;
  animation: tabUnderline 0.3s ease forwards;
}

.buffer-content {
  flex: 1;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  contain: layout style;
  background: var(--bg-primary);
}

/* ── Main Area ── */

.main {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  background: var(--bg-primary);
  contain: layout style;
}

.mobile-sidebar-scrim,
.mobile-bottom-overlay {
  display: none;
}

@media (max-width: 980px) {
  .app.mobile-layout {
    padding-top: env(safe-area-inset-top);
    padding-bottom: env(safe-area-inset-bottom);
  }

  .app.mobile-layout .sidebar {
    position: fixed;
    inset: env(safe-area-inset-top) auto env(safe-area-inset-bottom) 0;
    width: min(85vw, 320px);
    min-width: min(85vw, 320px);
    z-index: 30;
    transform: translateX(-102%);
    transition: transform 0.24s ease;
    border-right: 1px solid var(--border-color);
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.35);
  }

  .app.mobile-layout.sidebar-dragging .sidebar {
    transition: none;
  }

  .app.mobile-layout.mobile-sidebar-open .sidebar {
    transform: translateX(0);
  }

  .app.mobile-layout .main {
    width: 100%;
    padding-bottom: calc(58px + env(safe-area-inset-bottom) + var(--keyboard-offset, 0px));
  }

  .desktop-only-tabs {
    display: none;
  }

  .mobile-sidebar-scrim {
    display: block;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.48);
    transition: background-color 0.24s ease;
    z-index: 20;
    border: none;
    border-radius: 0;
    padding: 0;
    margin: 0;
  }

  .app.mobile-layout.sidebar-dragging .mobile-sidebar-scrim {
    transition: none;
  }

  .mobile-bottom-overlay {
    display: grid;
    grid-template-columns: repeat(5, minmax(0, 1fr));
    gap: 6px;
    align-items: center;
    position: fixed;
    left: 8px;
    right: 8px;
    bottom: calc(6px + env(safe-area-inset-bottom) + var(--keyboard-offset, 0px));
    z-index: 40;
    padding: 6px;
    border-radius: 12px;
    background: rgba(25, 25, 24, 0.92);
    border: 1px solid var(--border-color);
    backdrop-filter: blur(8px);
  }

  .mobile-action-btn {
    min-height: 36px;
    border: 1px solid var(--border-color);
    background: var(--bg-primary);
    color: var(--text-secondary);
    font-size: 16px;
    line-height: 1;
    letter-spacing: 0.02em;
    padding: 0;
  }

  .mobile-action-btn.active {
    color: var(--accent);
    border-color: var(--accent-border);
    background: var(--bg-tertiary);
  }
}

/* ── Buffer panes: active vs hidden ── */

.buffer-pane {
  contain: strict;
  will-change: transform;
  background: var(--bg-primary);
}

.buffer-pane.hidden {
  content-visibility: hidden;
  /* content-visibility: hidden skips rendering entirely while keeping the
     element in the DOM.  Unlike display: none this doesn't destroy layout
     state, and unlike visibility: hidden it avoids all rendering work
     including layout, paint, and compositing — eliminating resize cost
     for inactive buffers. */
}

.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  gap: 8px;
  animation: fadeIn 0.4s ease;
  position: relative;
}

/* Warm glow behind empty state */
.empty-state::before {
  content: '';
  position: absolute;
  width: 280px;
  height: 180px;
  background: radial-gradient(ellipse, rgba(196, 168, 130, 0.06) 0%, transparent 70%);
  border-radius: 50%;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -60%);
  pointer-events: none;
  animation: warmPulse 4s ease-in-out infinite;
}

.empty-state h2 {
  font-family: var(--font-serif);
  color: var(--text-secondary);
  font-size: 20px;
  font-weight: 500;
  letter-spacing: -0.01em;
}

.empty-state p {
  margin: 0;
}

.empty-state button {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  padding: 10px 20px;
  font-weight: 500;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  margin-top: 4px;
  transition: background 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.empty-state button:hover:not(:disabled) {
  background: var(--bg-hover);
  border-color: var(--accent-border);
  box-shadow: var(--glow);
}