frontend/src/index.css

/* ============================================
   RAG Knowledge Assistant - Design System
   ============================================ */

/* CSS Reset & Base */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  /* Colors - Dark Theme */
  --bg-primary: #0a0a0f;
  --bg-secondary: #12121a;
  --bg-tertiary: #1a1a24;
  --bg-elevated: #22222e;
  --bg-glass: rgba(255, 255, 255, 0.03);
  --bg-glass-hover: rgba(255, 255, 255, 0.06);
  
  /* Accent Colors */
  --accent-primary: #6366f1;
  --accent-secondary: #818cf8;
  --accent-tertiary: #a5b4fc;
  --accent-gradient: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #a855f7 100%);
  --accent-glow: 0 0 20px rgba(99, 102, 241, 0.4);
  
  /* Text Colors */
  --text-primary: #f4f4f5;
  --text-secondary: #a1a1aa;
  --text-tertiary: #71717a;
  --text-inverse: #09090b;
  
  /* Border Colors */
  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-medium: rgba(255, 255, 255, 0.12);
  --border-accent: rgba(99, 102, 241, 0.4);
  
  /* Status Colors */
  --success: #22c55e;
  --success-bg: rgba(34, 197, 94, 0.1);
  --error: #ef4444;
  --error-bg: rgba(239, 68, 68, 0.1);
  --warning: #f59e0b;
  --warning-bg: rgba(245, 158, 11, 0.1);
  --info: #3b82f6;
  --info-bg: rgba(59, 130, 246, 0.1);
  
  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  
  /* Font Sizes */
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  
  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  
  /* Border Radius */
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-2xl: 24px;
  --radius-full: 9999px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -4px rgba(0, 0, 0, 0.4);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.5), 0 8px 10px -6px rgba(0, 0, 0, 0.4);
  --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.15);
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease;
  --transition-slow: 300ms ease;
  --transition-spring: 300ms cubic-bezier(0.34, 1.56, 0.64, 1);
  
  /* Layout */
  --sidebar-width: 280px;
  --topnav-height: 64px;
  --chat-max-width: 800px;
}

/* Base Styles */
html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  overflow: hidden;
}

#root {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Scrollbar Styling */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--border-medium);
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-tertiary);
}

/* Focus Styles */
:focus-visible {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

/* Selection */
::selection {
  background: rgba(99, 102, 241, 0.3);
  color: var(--text-primary);
}

/* ============================================
   Utility Classes
   ============================================ */

.glass {
  background: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-subtle);
}

.glass-strong {
  background: rgba(18, 18, 26, 0.8);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--border-subtle);
}

/* ============================================
   Button Styles
   ============================================ */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-5);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  font-weight: 500;
  border-radius: var(--radius-lg);
  border: none;
  cursor: pointer;
  transition: all var(--transition-base);
  text-decoration: none;
  white-space: nowrap;
}

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

.btn-primary {
  background: var(--accent-gradient);
  color: white;
  box-shadow: var(--shadow-md), 0 0 20px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover:not(:disabled) {
  transform: translateY(-1px);
  box-shadow: var(--shadow-lg), 0 0 30px rgba(99, 102, 241, 0.4);
}

.btn-primary:active:not(:disabled) {
  transform: translateY(0);
}

.btn-secondary {
  background: var(--bg-glass);
  color: var(--text-primary);
  border: 1px solid var(--border-subtle);
}

.btn-secondary:hover:not(:disabled) {
  background: var(--bg-glass-hover);
  border-color: var(--border-medium);
}

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

.btn-ghost:hover:not(:disabled) {
  background: var(--bg-glass);
  color: var(--text-primary);
}

.btn-icon {
  padding: var(--space-2);
  border-radius: var(--radius-md);
}

.btn-sm {
  padding: var(--space-2) var(--space-3);
  font-size: var(--text-xs);
}

.btn-lg {
  padding: var(--space-4) var(--space-6);
  font-size: var(--text-base);
}

/* ============================================
   Input Styles
   ============================================ */

.input {
  width: 100%;
  padding: var(--space-3) var(--space-4);
  font-family: var(--font-sans);
  font-size: var(--text-base);
  color: var(--text-primary);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  transition: all var(--transition-base);
}

.input::placeholder {
  color: var(--text-tertiary);
}

.input:hover {
  border-color: var(--border-medium);
}

.input:focus {
  outline: none;
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.15);
}

/* ============================================
   Card Styles
   ============================================ */

.card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
}

.card-glass {
  background: var(--bg-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
}

/* ============================================
   Animation Keyframes
   ============================================ */

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

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes slideInRight {
  from {
    opacity: 0;
    transform: translateX(-10px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes pulse {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.5;
  }
}

@keyframes bounce {
  0%, 80%, 100% {
    transform: translateY(0);
  }
  40% {
    transform: translateY(-6px);
  }
}

@keyframes shimmer {
  0% {
    background-position: -200% 0;
  }
  100% {
    background-position: 200% 0;
  }
}

@keyframes spin {
  from {
    transform: rotate(0deg);
  }
  to {
    transform: rotate(360deg);
  }
}

/* Animation Classes */
.animate-fade-in {
  animation: fadeIn var(--transition-base) ease forwards;
}

.animate-fade-in-up {
  animation: fadeInUp var(--transition-slow) ease forwards;
}

.animate-slide-in-right {
  animation: slideInRight var(--transition-slow) ease forwards;
}

.animate-pulse {
  animation: pulse 2s ease-in-out infinite;
}

.animate-spin {
  animation: spin 1s linear infinite;
}

/* Skeleton Loading */
.skeleton {
  background: linear-gradient(
    90deg,
    var(--bg-tertiary) 0%,
    var(--bg-elevated) 50%,
    var(--bg-tertiary) 100%
  );
  background-size: 200% 100%;
  animation: shimmer 1.5s ease-in-out infinite;
  border-radius: var(--radius-md);
}

/* ============================================
   Layout Components
   ============================================ */

.app-layout {
  display: grid;
  grid-template-rows: var(--topnav-height) 1fr;
  grid-template-columns: var(--sidebar-width) 1fr;
  height: 100vh;
  overflow: hidden;
}

.app-layout.sidebar-collapsed {
  grid-template-columns: 0 1fr;
}

/* ============================================
   Badge Styles
   ============================================ */

.badge {
  display: inline-flex;
  align-items: center;
  padding: var(--space-1) var(--space-2);
  font-size: var(--text-xs);
  font-weight: 500;
  border-radius: var(--radius-full);
  background: var(--bg-glass);
  color: var(--text-secondary);
  border: 1px solid var(--border-subtle);
}

.badge-success {
  background: var(--success-bg);
  color: var(--success);
  border-color: rgba(34, 197, 94, 0.2);
}

.badge-error {
  background: var(--error-bg);
  color: var(--error);
  border-color: rgba(239, 68, 68, 0.2);
}

.badge-warning {
  background: var(--warning-bg);
  color: var(--warning);
  border-color: rgba(245, 158, 11, 0.2);
}

.badge-info {
  background: var(--info-bg);
  color: var(--info);
  border-color: rgba(59, 130, 246, 0.2);
}

/* ============================================
   Responsive Breakpoints
   ============================================ */

@media (max-width: 1024px) {
  :root {
    --sidebar-width: 240px;
  }
}

@media (max-width: 768px) {
  :root {
    --sidebar-width: 0;
    --topnav-height: 56px;
  }
  
  .app-layout {
    grid-template-columns: 1fr;
  }
}