@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@300;400;500;600;700&family=Noto+Sans+TC:wght@300;400;500;700&display=swap');

:root {
  /* Dark Mode Palette (Default) */
  --bg-primary: #0a0e1a;
  --bg-secondary: #111827;
  --glass-bg: rgba(255, 255, 255, 0.03);
  --glass-border: rgba(255, 255, 255, 0.07);
  --glass-highlight: rgba(255, 255, 255, 0.05);
  
  --text-primary: #f3f4f6;
  --text-secondary: #9ca3af;
  --text-muted: #6b7280;
  
  --accent-primary: #6366f1;
  --accent-secondary: #3b82f6;
  --accent-gradient: linear-gradient(135deg, #6366f1, #3b82f6);
  --accent-gradient-hover: linear-gradient(135deg, #4f46e5, #2563eb);
  
  --success: #10b981;
  --success-glow: rgba(16, 185, 129, 0.2);
  --danger: #ef4444;
  --danger-glow: rgba(239, 68, 68, 0.2);
  --warning: #f59e0b;
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.2), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.3), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  
  --font-sans: 'Outfit', 'Noto Sans TC', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
}

[data-theme="light"] {
  /* Light Mode Palette */
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --glass-bg: rgba(255, 255, 255, 0.7);
  --glass-border: rgba(0, 0, 0, 0.08);
  --glass-highlight: rgba(0, 0, 0, 0.02);
  
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  
  --accent-primary: #4f46e5;
  --accent-secondary: #2563eb;
  --accent-gradient: linear-gradient(135deg, #4f46e5, #2563eb);
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.02);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -1px rgba(0, 0, 0, 0.03);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.05), 0 4px 6px -2px rgba(0, 0, 0, 0.02);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.08), 0 10px 10px -5px rgba(0, 0, 0, 0.03);
}

/* Global Reset & Base Styling */

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-sans);
  min-height: 100vh;
  line-height: 1.5;
  overflow-x: hidden;
  transition: background-color 0.3s ease, color 0.3s ease;
}

/* Ambient Background Lights */

.bg-ambient-lights {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: -1;
  pointer-events: none;
  overflow: hidden;
  background: radial-gradient(circle at 10% 20%, rgba(99, 102, 241, 0.05) 0%, transparent 40%),
              radial-gradient(circle at 90% 80%, rgba(59, 130, 246, 0.05) 0%, transparent 40%);
}

[data-theme="light"] .bg-ambient-lights {
  background: radial-gradient(circle at 10% 20%, rgba(99, 102, 241, 0.02) 0%, transparent 40%),
              radial-gradient(circle at 90% 80%, rgba(59, 130, 246, 0.02) 0%, transparent 40%);
}

/* Glassmorphism Styles */

.glass {
  background: var(--glass-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--glass-border);
  box-shadow: var(--shadow-lg);
  border-radius: var(--radius-lg);
}

.glass-card {
  background: var(--glass-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-md);
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), box-shadow 0.3s ease, border-color 0.3s ease;
}

.glass-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-xl);
  border-color: rgba(99, 102, 241, 0.2);
}

/* Typography & Headers */

h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  letter-spacing: -0.02em;
}

.title-gradient {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Buttons */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-family: var(--font-sans);
  font-weight: 500;
  padding: 10px 20px;
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  text-decoration: none;
}

.btn-primary {
  background: var(--accent-gradient);
  color: #ffffff;
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover {
  opacity: 0.95;
  transform: translateY(-1px);
  box-shadow: 0 6px 16px rgba(99, 102, 241, 0.4);
}

.btn-primary:active {
  transform: translateY(0);
}

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

.btn-secondary:hover {
  background: var(--glass-highlight);
  border-color: var(--text-secondary);
}

.btn-danger {
  background: var(--danger);
  color: #ffffff;
  box-shadow: 0 4px 12px var(--danger-glow);
}

.btn-danger:hover {
  opacity: 0.95;
  transform: translateY(-1px);
}

.btn-text {
  background: transparent;
  color: var(--text-secondary);
  padding: 6px 12px;
}

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

/* Inputs & Form Controls */

.form-group {
  margin-bottom: 20px;
}

.form-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

.input {
  width: 100%;
  padding: 12px 16px;
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 1rem;
  outline: none;
  transition: all 0.2s ease;
}

.input:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.15);
}

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

.input-checkbox {
  width: 18px;
  height: 18px;
  accent-color: var(--accent-primary);
  cursor: pointer;
}

/* Layout Utilities */

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.grid {
  display: grid;
  gap: 24px;
}

.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }

.grid-cols-3 { grid-template-columns: repeat(3, 1fr); }

.grid-cols-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 900px) {
  .grid-cols-3, .grid-cols-4 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 600px) {
  .grid-cols-2, .grid-cols-3, .grid-cols-4 { grid-template-columns: 1fr; }
}

/* Animations */

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

.animate-fade-in {
  animation: fadeIn 0.4s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

/* Custom Collapsible details/summary */

.collapsible-container {
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: rgba(0, 0, 0, 0.1);
  margin-top: 12px;
}

.collapsible-trigger {
  padding: 12px 16px;
  background: var(--glass-bg);
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  user-select: none;
  font-weight: 500;
  transition: background 0.2s ease;
}

.collapsible-trigger:hover {
  background: var(--glass-highlight);
}

.collapsible-content {
  padding: 16px;
  border-top: 1px solid var(--glass-border);
  animation: fadeIn 0.3s ease;
}

/* Print CSS Stylesheet */

@media print {
  body {
    background: #ffffff !important;
    color: #000000 !important;
    font-size: 12pt;
    font-family: 'Noto Sans TC', sans-serif !important;
  }
  
  .bg-ambient-lights,
  header,
  nav,
  .no-print,
  .btn,
  .theme-toggle,
  .collapsible-trigger svg,
  .sidebar,
  .filters-container {
    display: none !important;
  }

  .container {
    max-width: 100% !important;
    width: 100% !important;
    margin: 0 !important;
    padding: 0 !important;
  }

  .print-page {
    page-break-after: always;
  }

  /* Force display of answers in Complete/解析 mode during print */
  .print-solution-mode .collapsible-content {
    display: block !important;
    border-top: 1px dashed #cccccc !important;
    margin-top: 10px !important;
    padding-top: 10px !important;
  }

  /* Force hide answers in Practice/練習 mode during print */
  .print-practice-mode .collapsible-container,
  .print-practice-mode .collapsible-content,
  .print-practice-mode .answer-section {
    display: none !important;
  }

  .mistake-card-print {
    border: 1px solid #000000 !important;
    border-radius: 4px !important;
    padding: 15px !important;
    margin-bottom: 25px !important;
    page-break-inside: avoid !important;
    background: transparent !important;
    box-shadow: none !important;
  }

  .mistake-card-print h3 {
    border-bottom: 1px solid #000000 !important;
    padding-bottom: 5px !important;
    margin-bottom: 10px !important;
  }

  .print-grid {
    display: grid !important;
    grid-template-columns: 1fr !important;
    gap: 15px !important;
  }

  img {
    max-width: 80% !important;
    max-height: 4in !important;
    display: block !important;
    margin: 10px 0 !important;
    page-break-inside: avoid !important;
  }
}

/* ========================================
   Modal Overlay & Content
   ======================================== */

.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: 20px;
}

.modal-content {
  position: relative;
  max-height: 90vh;
  overflow-y: auto;
}

/* ========================================
   Sidebar Transitions
   ======================================== */

.sidebar {
  transition: width 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.sidebar-collapsed {
  width: 48px !important;
}

.sidebar-expanded {
  width: 300px;
}

/* ========================================
   Spin Animation (for loaders)
   ======================================== */

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

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

/* ========================================
   Responsive Layout
   ======================================== */

/* Mobile: <768px */

@media (max-width: 767px) {
  /* Navbar responsive */
  .top-navbar {
    height: auto !important;
    min-height: 56px;
    padding: 8px 12px !important;
    flex-wrap: wrap;
    gap: 8px;
  }

  .navbar-brand {
    flex: 1;
    min-width: 0;
  }

  .navbar-title {
    font-size: 1rem !important;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  .navbar-actions {
    flex-wrap: wrap;
    gap: 6px !important;
    justify-content: flex-end;
  }

  .navbar-btn-text {
    display: none;
  }

  .navbar-user-info {
    display: none;
  }

  /* Sidebar defaults collapsed on mobile */
  .sidebar-expanded {
    position: fixed;
    left: 0;
    top: 56px;
    z-index: 40;
    width: 280px !important;
    height: calc(100vh - 56px) !important;
    box-shadow: 4px 0 24px rgba(0, 0, 0, 0.3);
    background: var(--bg-secondary) !important;
  }

  .sidebar-collapsed {
    width: 40px !important;
  }

  /* Main content full width */
  .main-layout {
    flex-direction: row;
  }

  /* Glass card adjustments */
  .glass-card {
    padding: 16px;
  }

  .glass {
    padding: 16px;
  }

  /* Table responsive */
  .glass-card table {
    font-size: 0.8rem;
  }

  .glass-card th, .glass-card td {
    padding: 8px 10px !important;
  }
}

/* Tablet: 768px - 1024px */

@media (min-width: 768px) and (max-width: 1024px) {
  .sidebar-expanded {
    width: 240px !important;
  }

  .navbar-btn-text {
    display: none;
  }

  .top-navbar {
    padding: 0 16px !important;
  }

  .glass-card {
    padding: 20px;
  }
}

/* Desktop: >1024px */

@media (min-width: 1025px) {
  .sidebar-expanded {
    width: 300px;
  }
}