:root {
  /* Colors */
  --color-background: rgba(252, 252, 249, 1);
  --color-surface: rgba(255, 255, 253, 1);
  --color-text: rgba(19, 52, 59, 1);
  --color-text-secondary: rgba(98, 108, 113, 1);
  --color-primary: rgba(33, 128, 141, 1);
  --color-primary-hover: rgba(29, 116, 128, 1);
  --color-primary-active: rgba(26, 104, 115, 1);
  --color-secondary: rgba(94, 82, 64, 0.12);
  --color-secondary-hover: rgba(94, 82, 64, 0.2);
  --color-secondary-active: rgba(94, 82, 64, 0.25);
  --color-border: rgba(94, 82, 64, 0.2);
  --color-btn-primary-text: rgba(252, 252, 249, 1);
  --color-card-border: rgba(94, 82, 64, 0.12);
  --color-card-border-inner: rgba(94, 82, 64, 0.12);
  --color-error: rgba(192, 21, 47, 1);
  --color-success: rgba(33, 128, 141, 1);
  --color-warning: rgba(168, 75, 47, 1);
  --color-info: rgba(98, 108, 113, 1);
  --color-focus-ring: rgba(33, 128, 141, 0.4);
  --color-select-caret: rgba(19, 52, 59, 0.8);

  /* Common style patterns */
  --focus-ring: 0 0 0 3px var(--color-focus-ring);
  --focus-outline: 2px solid var(--color-primary);
  --status-bg-opacity: 0.15;
  --status-border-opacity: 0.25;
  --select-caret-light: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%23134252' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
  --select-caret-dark: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%23f5f5f5' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");

  /* RGB versions for opacity control */
  --color-success-rgb: 33, 128, 141;
  --color-error-rgb: 192, 21, 47;
  --color-warning-rgb: 168, 75, 47;
  --color-info-rgb: 98, 108, 113;

  /* Typography */
  --font-family-base: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-family-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  --font-size-xs: 11px;
  --font-size-sm: 12px;
  --font-size-base: 14px;
  --font-size-md: 14px;
  --font-size-lg: 16px;
  --font-size-xl: 18px;
  --font-size-2xl: 20px;
  --font-size-3xl: 24px;
  --font-size-4xl: 30px;
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 550;
  --font-weight-bold: 600;
  --line-height-tight: 1.2;
  --line-height-normal: 1.5;
  --letter-spacing-tight: -0.01em;

  /* Spacing */
  --space-0: 0;
  --space-1: 1px;
  --space-2: 2px;
  --space-4: 4px;
  --space-6: 6px;
  --space-8: 8px;
  --space-10: 10px;
  --space-12: 12px;
  --space-16: 16px;
  --space-20: 20px;
  --space-24: 24px;
  --space-32: 32px;

  /* Border Radius */
  --radius-sm: 6px;
  --radius-base: 8px;
  --radius-md: 10px;
  --radius-lg: 12px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.02);
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.04), 0 1px 2px rgba(0, 0, 0, 0.02);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.04), 0 2px 4px -1px rgba(0, 0, 0, 0.02);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.04), 0 4px 6px -2px rgba(0, 0, 0, 0.02);
  --shadow-inset-sm: inset 0 1px 0 rgba(255, 255, 255, 0.15), inset 0 -1px 0 rgba(0, 0, 0, 0.03);

  /* Animation */
  --duration-fast: 150ms;
  --duration-normal: 250ms;
  --ease-standard: cubic-bezier(0.16, 1, 0.3, 1);

  /* Layout */
  --container-sm: 640px;
  --container-md: 768px;
  --container-lg: 1024px;
  --container-xl: 1280px;
}

/* Dark mode colors */
@media (prefers-color-scheme: dark) {
  :root {
    --color-background: rgba(31, 33, 33, 1);
    --color-surface: rgba(38, 40, 40, 1);
    --color-text: rgba(245, 245, 245, 1);
    --color-text-secondary: rgba(167, 169, 169, 0.7);
    --color-primary: rgba(50, 184, 198, 1);
    --color-primary-hover: rgba(45, 166, 178, 1);
    --color-primary-active: rgba(41, 150, 161, 1);
    --color-secondary: rgba(119, 124, 124, 0.15);
    --color-secondary-hover: rgba(119, 124, 124, 0.25);
    --color-secondary-active: rgba(119, 124, 124, 0.3);
    --color-border: rgba(119, 124, 124, 0.3);
    --color-error: rgba(255, 84, 89, 1);
    --color-success: rgba(50, 184, 198, 1);
    --color-warning: rgba(230, 129, 97, 1);
    --color-info: rgba(167, 169, 169, 1);
    --color-focus-ring: rgba(50, 184, 198, 0.4);
    --color-btn-primary-text: rgba(19, 52, 59, 1);
    --color-card-border: rgba(119, 124, 124, 0.2);
    --color-card-border-inner: rgba(119, 124, 124, 0.15);
    --shadow-inset-sm: inset 0 1px 0 rgba(255, 255, 255, 0.1), inset 0 -1px 0 rgba(0, 0, 0, 0.15);
    --button-border-secondary: rgba(119, 124, 124, 0.2);
    --color-border-secondary: rgba(119, 124, 124, 0.2);
    --color-select-caret: rgba(245, 245, 245, 0.8);

    /* RGB versions for dark mode */
    --color-success-rgb: 50, 184, 198;
    --color-error-rgb: 255, 84, 89;
    --color-warning-rgb: 230, 129, 97;
    --color-info-rgb: 167, 169, 169;
  }
}

/* Base styles */
html {
  font-size: var(--font-size-base);
  font-family: var(--font-family-base);
  line-height: var(--line-height-normal);
  color: var(--color-text);
  background-color: var(--color-background);
  -webkit-font-smoothing: antialiased;
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 0;
}

*, *::before, *::after {
  box-sizing: inherit;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  margin: 0;
  font-weight: var(--font-weight-semibold);
  line-height: var(--line-height-tight);
  color: var(--color-text);
  letter-spacing: var(--letter-spacing-tight);
}

h1 { font-size: var(--font-size-4xl); }
h2 { font-size: var(--font-size-3xl); }
h3 { font-size: var(--font-size-2xl); }
h4 { font-size: var(--font-size-xl); }
h5 { font-size: var(--font-size-lg); }
h6 { font-size: var(--font-size-md); }

p {
  margin: 0 0 var(--space-16) 0;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--duration-fast) var(--ease-standard);
}

a:hover {
  color: var(--color-primary-hover);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-8) var(--space-16);
  border-radius: var(--radius-base);
  font-size: var(--font-size-base);
  font-weight: 500;
  line-height: 1.5;
  cursor: pointer;
  transition: all var(--duration-normal) var(--ease-standard);
  border: none;
  text-decoration: none;
  position: relative;
}

.btn:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
}

.btn--primary {
  background: var(--color-primary);
  color: var(--color-btn-primary-text);
}

.btn--primary:hover {
  background: var(--color-primary-hover);
}

.btn--primary:active {
  background: var(--color-primary-active);
}

.btn--secondary {
  background: var(--color-secondary);
  color: var(--color-text);
}

.btn--secondary:hover {
  background: var(--color-secondary-hover);
}

.btn--secondary:active {
  background: var(--color-secondary-active);
}

.btn--outline {
  background: transparent;
  border: 1px solid var(--color-border);
  color: var(--color-text);
}

.btn--outline:hover {
  background: var(--color-secondary);
}

.btn--sm {
  padding: var(--space-4) var(--space-12);
  font-size: var(--font-size-sm);
  border-radius: var(--radius-sm);
}

.btn--lg {
  padding: var(--space-10) var(--space-20);
  font-size: var(--font-size-lg);
  border-radius: var(--radius-md);
}

.btn--full-width {
  width: 100%;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn i {
  margin-right: var(--space-4);
}

.btn:last-child i,
.btn--sm i {
  margin-right: 0;
}

/* Form elements */
.form-control {
  display: block;
  width: 100%;
  padding: var(--space-8) var(--space-12);
  font-size: var(--font-size-md);
  line-height: 1.5;
  color: var(--color-text);
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-base);
  transition: border-color var(--duration-fast) var(--ease-standard), box-shadow var(--duration-fast) var(--ease-standard);
}

select.form-control {
  padding: var(--space-8) var(--space-12);
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  background-image: var(--select-caret-light);
  background-repeat: no-repeat;
  background-position: right var(--space-12) center;
  background-size: 16px;
  padding-right: var(--space-32);
}

@media (prefers-color-scheme: dark) {
  select.form-control {
    background-image: var(--select-caret-dark);
  }
}

.form-control:focus {
  border-color: var(--color-primary);
  outline: var(--focus-outline);
}

.form-label {
  display: block;
  margin-bottom: var(--space-8);
  font-weight: var(--font-weight-medium);
  font-size: var(--font-size-sm);
}

.form-group {
  margin-bottom: var(--space-16);
}

/* Card component */
.card {
  background-color: var(--color-surface);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-card-border);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: box-shadow var(--duration-normal) var(--ease-standard);
}

.card:hover {
  box-shadow: var(--shadow-md);
}

.card__body {
  padding: var(--space-16);
}

.card__header {
  padding: var(--space-16);
  border-bottom: 1px solid var(--color-card-border-inner);
}

/* Container layout */
.container {
  width: 100%;
  margin-right: auto;
  margin-left: auto;
  padding-right: var(--space-16);
  padding-left: var(--space-16);
}

@media (min-width: 640px) { .container { max-width: var(--container-sm); } }
@media (min-width: 768px) { .container { max-width: var(--container-md); } }
@media (min-width: 1024px) { .container { max-width: var(--container-lg); } }
@media (min-width: 1280px) { .container { max-width: var(--container-xl); } }

/* Utility classes */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-4 { gap: var(--space-4); }
.gap-8 { gap: var(--space-8); }
.gap-16 { gap: var(--space-16); }

.mb-8 { margin-bottom: var(--space-8); }
.block { display: block; }
.hidden { display: none; }

/* Accessibility */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

:focus-visible {
  outline: var(--focus-outline);
  outline-offset: 2px;
}

/* Custom styles building on the design system */
.app-container {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: linear-gradient(135deg, var(--color-background) 0%, var(--color-surface) 100%);
}

/* Header Styles */
.header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
  padding: var(--space-16) 0;
  position: sticky;
  top: 0;
  z-index: 100;
}

.logo-container {
  display: flex;
  align-items: center;
  gap: var(--space-12);
}

.logo {
  font-size: var(--font-size-4xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-primary);
  margin: 0;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-hover) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.tagline {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  font-weight: var(--font-weight-medium);
}

/* Main Content Layout */
.main-content {
  flex: 1;
  padding: var(--space-24) var(--space-16);
}

.content-wrapper {
  display: grid;
  grid-template-columns: 300px 1fr;
  gap: var(--space-24);
  height: calc(100vh - 200px);
  max-height: 800px;
}

/* Sidebar Styles */
.sidebar {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-card-border);
  box-shadow: var(--shadow-md);
  padding: var(--space-20);
  overflow-y: auto;
  height: fit-content;
  max-height: 100%;
}

.sidebar-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-20);
  padding-bottom: var(--space-12);
  border-bottom: 1px solid var(--color-border);
}

.sidebar-header h3 {
  color: var(--color-primary);
  margin: 0;
}

.sidebar-section {
  margin-bottom: var(--space-24);
}

.sidebar-section h4 {
  font-size: var(--font-size-md);
  font-weight: var(--font-weight-semibold);
  color: var(--color-text);
  margin-bottom: var(--space-12);
}

.sidebar-section:last-child {
  margin-bottom: 0;
}

/* Quick Queries */
.quick-queries {
  display: flex;
  flex-direction: column;
  gap: var(--space-8);
}

.query-btn {
  background: var(--color-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-base);
  padding: var(--space-8) var(--space-12);
  text-align: left;
  cursor: pointer;
  font-size: var(--font-size-sm);
  color: var(--color-text);
  transition: all var(--duration-fast) var(--ease-standard);
}

.query-btn:hover {
  background: var(--color-secondary-hover);
  transform: translateY(-1px);
}

/* Chat Area - UPDATED */
.chat-area {
  display: flex;
  flex-direction: column;
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-card-border);
  box-shadow: var(--shadow-md);
  overflow: hidden;
  position: relative;
  min-height: 400px;
  max-height: calc(100vh - 200px);
}

.chat-container {
  flex: 1;
  padding: var(--space-20);
  padding-bottom: calc(var(--space-20) + 80px); /* Add bottom padding to prevent content overlap */
  overflow-y: auto;
  min-height: 300px;
  max-height: calc(100vh - 350px); /* Adjusted to account for input container */
  display: flex;
  flex-direction: column;
  gap: var(--space-16);
}

/* Message Bubbles */
.message {
  display: flex;
  margin-bottom: var(--space-16);
  animation: fadeInUp 0.3s ease-out;
}

.message.user {
  justify-content: flex-end;
}

.message.bot {
  justify-content: flex-start;
}

.message-bubble {
  max-width: 70%;
  padding: var(--space-12) var(--space-16);
  border-radius: var(--radius-lg);
  position: relative;
  box-shadow: var(--shadow-sm);
}

.message.user .message-bubble {
  background: var(--color-primary);
  color: var(--color-btn-primary-text);
  border-bottom-right-radius: var(--radius-sm);
}

.message.bot .message-bubble {
  background: var(--color-secondary);
  color: var(--color-text);
  border-bottom-left-radius: var(--radius-sm);
}

.message-content {
  margin: 0;
  line-height: var(--line-height-normal);
}

.message-time {
  font-size: var(--font-size-xs);
  opacity: 0.7;
  margin-top: var(--space-4);
}

.message-actions {
  display: flex;
  gap: var(--space-8);
  margin-top: var(--space-8);
}

.copy-btn {
  background: none;
  border: none;
  color: var(--color-text-secondary);
  cursor: pointer;
  font-size: var(--font-size-xs);
  padding: var(--space-2);
  border-radius: var(--radius-sm);
  transition: color var(--duration-fast);
}

.copy-btn:hover {
  color: var(--color-text);
}

/* Typing Indicator */
.typing-indicator {
  display: flex;
  justify-content: flex-start;
  margin-bottom: var(--space-16);
}

.typing-bubble {
  background: var(--color-secondary);
  padding: var(--space-12) var(--space-16);
  border-radius: var(--radius-lg);
  border-bottom-left-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.typing-dots {
  display: flex;
  gap: var(--space-2);
}

.typing-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-text-secondary);
  animation: typingDots 1.4s infinite ease-in-out;
}

.typing-dot:nth-child(1) { animation-delay: -0.32s; }
.typing-dot:nth-child(2) { animation-delay: -0.16s; }

/* Chat Input - UPDATED */
.chat-input-container {
  padding: var(--space-20);
  border-top: 1px solid var(--color-border);
  background: var(--color-surface);
  position: sticky;
  bottom: 0;
  z-index: 10;
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.1); /* Add subtle shadow for separation */
}

.input-wrapper {
  display: flex;
  gap: var(--space-12);
  align-items: flex-end;
}

.input-wrapper .form-control {
  flex: 1;
  resize: none;
  min-height: 44px;
  max-height: 120px;
}

#send-btn {
  flex-shrink: 0;
  height: 44px;
  width: 44px;
  border-radius: 50%;
  padding: 0;
}

/* Welcome Message */
.welcome-message {
  text-align: center;
  color: var(--color-text-secondary);
  padding: var(--space-32);
}

.welcome-message h3 {
  color: var(--color-primary);
  margin-bottom: var(--space-16);
}

.welcome-message ul {
  text-align: left;
  max-width: 400px;
  margin: var(--space-16) auto;
}

/* Footer */
.footer {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: var(--space-16) 0;
  margin-top: auto;
}

.footer p {
  margin: 0;
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

.footer a {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  text-decoration: none;
}

.footer a:hover {
  color: var(--color-primary);
}

/* Modal Styles */
.modal {
  display: none;
  position: fixed;
  z-index: 1000;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(4px);
}

.modal.show {
  display: flex;
  align-items: center;
  justify-content: center;
  animation: fadeIn 0.3s ease-out;
}

.modal-content {
  max-width: 500px;
  width: 90%;
  margin: var(--space-20);
  animation: slideInUp 0.3s ease-out;
}

.modal-close {
  cursor: pointer;
}

/* Responsive Design - UPDATED */
.mobile-only {
  display: none;
}

@media (max-width: 768px) {
  .content-wrapper {
    grid-template-columns: 1fr;
    gap: 0;
    height: calc(100vh - 150px); /* Adjusted for mobile */
  }
  
  .sidebar {
    position: fixed;
    top: 0;
    left: -100%;
    width: 280px;
    height: 100vh;
    z-index: 200;
    transition: left var(--duration-normal) var(--ease-standard);
    border-radius: 0;
    border-right: 1px solid var(--color-border);
    border-top: none;
    border-left: none;
    border-bottom: none;
  }
  
  .sidebar.show {
    left: 0;
  }
  
  .mobile-only {
    display: inline-flex;
  }
  
  .tagline {
    display: none;
  }
  
  .chat-container {
    min-height: 250px;
    max-height: calc(100vh - 300px); /* Better mobile spacing */
    padding-bottom: calc(var(--space-20) + 60px); /* Mobile-specific bottom padding */
  }
  
  .chat-input-container {
    padding: var(--space-16); /* Slightly less padding on mobile */
  }
  
  .message-bubble {
    max-width: 85%;
  }
}

/* Additional zoom handling - NEW */
@media (min-resolution: 1.5dppx) {
  .chat-input-container {
    padding-bottom: calc(var(--space-20) + 10px); /* Extra padding for high DPI displays */
  }
}

/* Animations */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideInUp {
  from {
    transform: translateY(30px);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

@keyframes typingDots {
  0%, 80%, 100% {
    transform: scale(0.8);
    opacity: 0.5;
  }
  40% {
    transform: scale(1);
    opacity: 1;
  }
}

/* Scrollbar Styling */
.chat-container::-webkit-scrollbar,
.sidebar::-webkit-scrollbar {
  width: 6px;
}

.chat-container::-webkit-scrollbar-track,
.sidebar::-webkit-scrollbar-track {
  background: var(--color-secondary);
  border-radius: var(--radius-sm);
}

.chat-container::-webkit-scrollbar-thumb,
.sidebar::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: var(--radius-sm);
}

.chat-container::-webkit-scrollbar-thumb:hover,
.sidebar::-webkit-scrollbar-thumb:hover {
  background: var(--color-text-secondary);
}

/* Status indicators */
.status-online {
  display: inline-flex;
  align-items: center;
  gap: var(--space-4);
  font-size: var(--font-size-sm);
  color: var(--color-success);
}

.status-online::before {
  content: '';
  width: 8px;
  height: 8px;
  background: var(--color-success);
  border-radius: 50%;
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0% {
    box-shadow: 0 0 0 0 rgba(var(--color-success-rgb), 0.7);
  }
  70% {
    box-shadow: 0 0 0 10px rgba(var(--color-success-rgb), 0);
  }
  100% {
    box-shadow: 0 0 0 0 rgba(var(--color-success-rgb), 0);
  }
}

/* Focus states for accessibility */
.query-btn:focus-visible,
#chat-input:focus-visible,
#syllabus-select:focus-visible {
  outline: var(--focus-outline);
  outline-offset: 2px;
}

/* Loading state */
.loading {
  opacity: 0.7;
  pointer-events: none;
}

/* Error states */
.error-message {
  color: var(--color-error);
  font-size: var(--font-size-sm);
  margin-top: var(--space-4);
}

/* Success states */
.success-message {
  color: var(--color-success);
  font-size: var(--font-size-sm);
  margin-top: var(--space-4);
}