/* initial light mode color scheme */
:root {
  --primary-color: #4a6cf7;
  --primary-dark: #3a56c5;
  --secondary-color: #6c757d;
  --background-color: #ffffff;
  --text-color: #333333;
  --light-gray: #f8f9fa;
  --border-color: #e9ecef;
  --success-color: #28a745;
  --warning-color: #ffc107;
  --danger-color: #dc3545;
  --info-color: #17a2b8;

  /* theme variables for card effects */
  --card-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
  --card-shadow-hover: 0 20px 40px rgba(0, 0, 0, 0.2);
  --card-border-radius: 8px;
  --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-bounce: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);

  /* Player */
  --player-bg: #fff;
  --player-border: #e9ecef;
  --player-text: #333;
  --player-muted: #6c757d;
  --player-accent: #4a6cf7;
  
  /* smooth transition for color changes */
  color-scheme: light;
}

/* Dark theme */
html.dark-theme {
  --primary-color: #5d7bf9;
  --primary-dark: #4a6cf7;
  --secondary-color: #a0a0a0;
  --background-color: #121212;
  --text-color: #f0f0f0;
  --light-gray: #1e1e1e;
  --border-color: #2d2d2d;

  /* dark theme card variables */
  --card-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
  --card-shadow-hover: 0 20px 40px rgba(0, 0, 0, 0.5);

  --player-bg: #1e1e1e;
  --player-border: #2d2d2d;
  --player-text: #f0f0f0;
  --player-muted: #cccccc;
  --player-accent: #5d7bf9;
  
  /* Setting dark color scheme to tell browsers we're in dark mode */
  color-scheme: dark;
}

/* For backward compatibility, keep the body class as well */
body.dark-theme {
  background-color: var(--background-color);
  color: var(--text-color);
}

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

/* Adding smooth transitions to all elements */
html {
  transition: background-color 0.3s ease, color 0.3s ease;
  background-color: var(--background-color);
  color: var(--text-color);
  min-height: 100%;
}

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background-color: var(--background-color);
  transition: background-color 0.3s ease, color 0.3s ease;
  min-height: 100vh;
}

a { color: var(--primary-color); text-decoration: none; transition: color 0.3s; }
a:hover { color: var(--primary-dark); }

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

h1, h2, h3, h4, h5, h6 { margin-bottom: 1rem; line-height: 1.3; color: var(--text-color); }

/* Site header with smoother transitions */
.site-header {
  background-color: var(--background-color);
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
  position: sticky;
  top: 0;
  z-index: 100;
  transition: background-color 0.3s ease, box-shadow 0.3s ease, transform 0.3s ease;
}

/* Header hidden state for scroll behavior */
.site-header.header-hidden {
  transform: translateY(-100%);
  box-shadow: none;
}
.site-header .container {
  display:flex; justify-content:space-between; align-items:center; padding:1rem 20px;
}
.header-left, .header-right { display:flex; align-items:center; }
.site-title { font-size:1.5rem; margin:0; }
.site-title a { color: var(--text-color); }
.site-nav { display:flex; gap:1.5rem; }
.site-nav a { color: var(--text-color); font-weight:500; }
.site-nav a:hover { color: var(--primary-color); }
.header-right { display:flex; gap:1rem; }
.theme-toggle, .menu-toggle {
  background: none; 
  border: none; 
  color: var(--text-color);
  font-size: 1.2rem; 
  cursor: pointer; 
  padding: 0.5rem; 
  transition: color 0.3s ease, transform 0.3s ease;
}

.theme-toggle:hover, .menu-toggle:hover { 
  color: var(--primary-color); 
  transform: scale(1.1);
}

/* animation for theme toggle */
.theme-toggle i {
  transition: transform 0.3s ease;
}

.theme-toggle:active i {
  transform: rotate(30deg);
}

/* Hero */
.hero { padding:4rem 0; background-color: var(--light-gray); text-align:center; margin-bottom: 3rem; }
.hero h1 { font-size:3rem; margin-bottom:1rem; }
.hero p { font-size:1.5rem; margin-bottom:2rem; color: var(--secondary-color); }

/* Cards reused from PYQFort */
.pdf-grid { display:grid; grid-template-columns: repeat(auto-fill, minmax(350px, 1fr)); gap:2rem; }
.pdf-card {
  display:flex; background-color: var(--background-color); border-radius: var(--card-border-radius);
  overflow:hidden; box-shadow: var(--card-shadow); 
  transition: var(--transition-bounce);
  transform-style: preserve-3d;
  position: relative;
}
.pdf-card:hover { 
  transform: translateY(-5px) perspective(1000px) rotateX(5deg);
  box-shadow:0 15px 30px rgba(0,0,0,0.15);
}
.pdf-icon {
  padding:2rem; font-size:2rem; display:flex; align-items:center; justify-content:center;
  background-color: var(--primary-color); color: #fff; min-width:80px;
}
.pdf-content { padding:1.5rem; flex-grow:1; }
.pdf-title { font-size:1.2rem; margin-bottom:1rem; }
.pdf-meta { margin-bottom:1.5rem; color: var(--secondary-color); font-size:0.9rem; display:flex; gap:1rem; flex-wrap:wrap; }

.btn-action {
  display:flex; align-items:center; gap:0.5rem; padding:0.5rem 1rem;
  background: var(--light-gray); border:1px solid var(--border-color); border-radius:6px;
  cursor:pointer; text-decoration:none; color: var(--text-color); font-size:0.9rem; 
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}
.btn-action:hover { background: #e9ecef; border-color: var(--primary-color); color: var(--primary-color); }
.btn-external { background: var(--info-color); color:#fff; border-color: var(--info-color); }
.btn-external:hover { background: var(--primary-dark); color:#fff; }

/* Breadcrumbs and headers reused */
.breadcrumbs { margin-bottom:2rem; color: var(--secondary-color); }
.breadcrumbs a { color: var(--secondary-color); }
.breadcrumbs a:hover { color: var(--primary-color); }

.pdf-viewer-header {
  background: var(--light-gray);
  padding: 2rem; border-radius: 12px; margin-bottom: 2rem; border:1px solid var(--border-color);
}
.pdf-title { font-size: 1.8rem; font-weight:700; margin-bottom:1rem; }
.pdf-meta span { margin-right: 1rem; }

/* Viewer options (repurposed for info line) */
.viewer-options {
  background: var(--background-color);
  border:1px solid var(--border-color);
  border-radius:8px; padding:1.5rem; margin-bottom:2rem;
}
.viewer-tabs { display:flex; gap:1rem; margin-bottom:1rem; }
.viewer-tab {
  display:flex; align-items:center; gap:0.5rem; padding:0.75rem 1.5rem;
  background: var(--light-gray); border:1px solid var(--border-color); border-radius:6px; cursor:pointer; font-weight:500; color: var(--text-color);
}
.viewer-tab.active { background: var(--primary-color); color:#fff; border-color: var(--primary-color); }
.viewer-info { padding:1rem; background: var(--light-gray); border-radius:6px; border-left:4px solid var(--primary-color); }
.viewer-description { display:flex; align-items:center; gap:0.5rem; font-size:0.9rem; color: var(--secondary-color); }

/* Actions bar */
.pdf-actions-bar {
  display:flex; justify-content: space-between; align-items:center;
  background: var(--background-color); border:1px solid var(--border-color);
  border-radius:8px; padding:1rem 1.5rem; margin-bottom:2rem;
}
.action-group { display:flex; gap:1rem; }

/* Audio Player */
.audio-player {
  display:flex; gap:1rem; padding:1rem; background: var(--player-bg);
  border:1px solid var(--player-border); border-radius:8px; align-items:center;
}
.player-cover img { width:100px; height:100px; object-fit:cover; border-radius:8px; border:1px solid var(--border-color); }
.player-main { flex:1; display:flex; flex-direction:column; gap:0.75rem; color: var(--player-text); }
.player-title { font-size:1.1rem; font-weight:600; }
.player-subtitle { color: var(--player-muted); font-size:0.9rem; }
.player-controls { display:flex; align-items:center; gap:0.75rem; }
.player-btn {
  background: var(--light-gray); border:1px solid var(--border-color);
  border-radius:6px; padding:0.5rem 0.75rem; cursor:pointer; color: var(--text-color);
}
.player-btn:hover { border-color: var(--player-accent); color: var(--player-accent); }
.player-time { margin-left:auto; color: var(--player-muted); font-size:0.9rem; }
.player-progress { display:flex; align-items:center; }
.seek-bar { width:100%; }
.player-extras { display:flex; align-items:center; gap:1rem; flex-wrap:wrap; }
.volume { display:flex; align-items:center; gap:0.5rem; }
.volume-bar { width:100px; }
.speed { display:flex; align-items:center; gap:0.5rem; }

/* Footer with smoother transitions */
.site-footer { 
  background-color: var(--light-gray); 
  padding: 3rem 0; 
  margin-top: 3rem; 
  transition: background-color 0.3s ease, color 0.3s ease; 
}
.footer-content { display:flex; flex-wrap:wrap; justify-content:space-between; margin-bottom:2rem; }
.footer-left { flex-basis:300px; flex-grow:1; margin-right:2rem; }
.footer-right { flex-grow:1; display:flex; flex-wrap:wrap; gap:2rem; }
.footer-links { min-width:200px; }
.footer-links h3 { margin-bottom:1.2rem; font-size:1.2rem; }
.footer-links ul { list-style:none; }
.footer-links li { margin-bottom:0.8rem; }
.footer-bottom { text-align:center; padding-top:2rem; border-top:1px solid var(--border-color); color: var(--secondary-color); }

/* Responsiveness */
@media (max-width: 992px) {
  .pdf-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 768px) {
  .site-header .container { flex-wrap:wrap; }
  .site-nav { display:none; width:100%; flex-direction:column; padding-top:1rem; margin-top:1rem; border-top:1px solid var(--border-color); }
  .site-nav.active { display:flex; }
  .menu-toggle { display:block; }
  .pdf-grid { grid-template-columns: 1fr; }
  .audio-player { flex-direction:column; align-items:stretch; }
  .player-time { margin-left:0; }
}

/* =============== ENHANCED CARD ANIMATIONS & RIPPLE EFFECTS =============== */

.animate-on-scroll {
  opacity: 0;
  transform: translateY(30px);
  transition: all 0.6s ease;
}

.animate-on-scroll.animate-in {
  opacity: 1;
  transform: translateY(0);
}

/* Enhanced card grid layouts */
.college-grid,
.branch-grid,
.semester-grid,
.subject-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
}

/* Enhanced card base styles with 3D effects */
.college-card,
.branch-card,
.semester-card,
.subject-card {
  display: flex;
  flex-direction: column;
  background-color: var(--background-color);
  border-radius: var(--card-border-radius);
  overflow: hidden;
  box-shadow: var(--card-shadow);
  transition: var(--transition-smooth);
  transform-style: preserve-3d;
  position: relative;
  cursor: pointer;
}

.college-card:hover,
.branch-card:hover,
.semester-card:hover,
.subject-card:hover {
  transform: translateY(-5px) perspective(1000px) rotateX(3deg);
  box-shadow: var(--card-shadow-hover);
}

/* Card icon sections with enhanced styling */
.college-icon,
.branch-icon,
.semester-icon {
  padding: 2rem;
  font-size: 3rem;
  text-align: center;
  color: white;
  transition: all 0.3s ease;
}

.college-icon {
  background-color: var(--primary-color);
}

.branch-icon {
  background-color: var(--success-color);
}

.semester-icon {
  background-color: var(--info-color);
}

/* Card content areas */
.college-content,
.branch-content,
.semester-content,
.subject-content {
  padding: 1.5rem;
  flex-grow: 1;
  display: flex;
  flex-direction: column;
}

.college-title,
.branch-title,
.semester-title,
.subject-title {
  font-size: 1.5rem;
  margin-bottom: 1rem;
}

.college-description,
.branch-description,
.semester-description,
.subject-description {
  margin-bottom: 1.5rem;
  flex-grow: 1;
}

.subject-meta,
.branch-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 1.5rem;
  color: var(--secondary-color);
  font-size: 0.9rem;
}

.subject-meta i,
.branch-meta i {
  margin-right: 0.5rem;
}

/* Enhanced button styles with ripple effect */
.btn,
.btn-view,
.btn-primary,
.btn-secondary {
  position: relative;
  overflow: hidden;
  display: inline-block;
  padding: 0.8rem 1.5rem;
  border-radius: 4px;
  font-weight: 500;
  text-align: center;
  transition: all 0.3s ease;
  cursor: pointer;
  border: none;
  text-decoration: none;
}

.btn-view,
.btn-primary {
  background-color: var(--primary-color);
  color: white;
}

.btn-view:hover,
.btn-primary:hover {
  background-color: var(--primary-dark);
  color: white;
  transform: translateY(-2px);
}

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

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

/* Ripple effect animation */
.ripple {
  position: absolute;
  border-radius: 50%;
  background: rgba(255,255,255,0.6);
  transform: scale(0);
  animation: ripple-animation 0.6s linear;
  pointer-events: none;
}

@keyframes ripple-animation {
  to {
    transform: scale(4);
    opacity: 0;
  }
}

/* Enhanced PDF card with better 3D effects */
.pdf-card {
  transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  border: 1px solid var(--border-color);
  background: var(--background-color);
  position: relative;
  overflow: hidden;
}

.pdf-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(45deg, transparent, rgba(255,255,255,0.1), transparent);
  transform: translateX(-100%);
  transition: transform 0.6s;
  pointer-events: none;
}

.pdf-card:hover::before {
  transform: translateX(100%);
}

.pdf-card:hover {
  transform: translateY(-8px) perspective(1000px) rotateX(5deg) rotateY(2deg);
  box-shadow: var(--card-shadow-hover), 0 0 20px rgba(74, 108, 247, 0.3);
  border-color: var(--primary-color);
}

.college-card:hover,
.branch-card:hover,
.semester-card:hover,
.subject-card:hover {
  transform: translateY(-5px) perspective(1000px) rotateX(3deg);
  box-shadow: var(--card-shadow-hover), 0 0 15px rgba(74, 108, 247, 0.2);
}

/* Enhanced PDF icon with gradient effect */
.pdf-icon {
  background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
  position: relative;
  overflow: hidden;
}

.pdf-icon::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(45deg, transparent, rgba(255,255,255,0.2), transparent);
  transform: translateX(-100%);
  transition: transform 0.6s;
}

.pdf-card:hover .pdf-icon::after {
  transform: translateX(100%);
}

/* Enhanced action buttons */
.pdf-actions {
  display: flex;
  gap: 0.5rem;
  margin-top: auto;
}

/* Enhanced tilt effect for interactive cards */
.card-tilt {
  transition: transform 0.2s ease-out;
}

.card-tilt:hover {
  transform-style: preserve-3d;
}

/* Podcast card specific enhancements */
.pdf-card .btn-external {
  background: linear-gradient(135deg, var(--info-color), #0ea5e9);
  border: none;
  position: relative;
  overflow: hidden;
}

.pdf-card .btn-external::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
  transition: left 0.5s;
}

.pdf-card .btn-external:hover::before {
  left: 100%;
}

/* Card title enhancements */
.pdf-title a {
  color: var(--text-color);
  transition: all 0.3s ease;
  position: relative;
}

.pdf-title a::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary-color);
  transition: width 0.3s ease;
}

.pdf-card:hover .pdf-title a::after {
  width: 100%;
}

/* Meta information styling */
.pdf-meta span {
  background: var(--light-gray);
  padding: 0.25rem 0.5rem;
  border-radius: 12px;
  font-size: 0.8rem;
  color: var(--secondary-color);
  transition: all 0.3s ease;
}

.pdf-card:hover .pdf-meta span {
  background: var(--primary-color);
  color: white;
  transform: translateY(-1px);
}

/* Filter buttons with enhanced styling */
.filter-btn {
  padding: 0.5rem 1rem;
  background-color: var(--light-gray);
  border: none;
  border-radius: 4px;
  cursor: pointer;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}

.filter-btn:hover,
.filter-btn.active {
  background-color: var(--primary-color);
  color: white;
  transform: translateY(-2px);
}

/* Loading animations for cards */
@keyframes cardSlideIn {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.card-slide-in {
  animation: cardSlideIn 0.6s ease-out;
}

/* Enhanced responsive design */
@media (max-width: 992px) {
  .college-grid,
  .subject-grid,
  .pdf-grid,
  .semester-grid,
  .branch-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .college-card:hover,
  .branch-card:hover,
  .semester-card:hover,
  .subject-card:hover,
  .pdf-card:hover {
    transform: translateY(-3px);
  }
}

@media (max-width: 768px) {
  .college-grid,
  .subject-grid,
  .pdf-grid,
  .semester-grid,
  .branch-grid {
    grid-template-columns: 1fr;
  }
  
  .college-card:hover,
  .branch-card:hover,
  .semester-card:hover,
  .subject-card:hover,
  .pdf-card:hover {
    transform: none;
    box-shadow: 0 8px 20px rgba(0,0,0,0.1);
  }
}


/* Enhanced Audio Player Styles */
.audio-player {
  display: flex;
  gap: 1rem;
  padding: 1.5rem;
  background: var(--player-bg);
  border: 1px solid var(--player-border);
  border-radius: 12px;
  align-items: flex-start;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  transition: all 0.3s ease;
}

.audio-player:hover {
  box-shadow: 0 6px 20px rgba(0,0,0,0.15);
}

.player-cover img {
  width: 120px;
  height: 120px;
  object-fit: cover;
  border-radius: 8px;
  border: 1px solid var(--border-color);
}

.player-main {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  color: var(--player-text);
  min-width: 0; /* Prevent flex overflow */
}

.player-title {
  font-size: 1.2rem;
  font-weight: 600;
  margin: 0;
  line-height: 1.3;
}

.player-subtitle {
  color: var(--player-muted);
  font-size: 0.9rem;
  margin: 0;
}

.player-controls {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.player-btn {
  background: var(--light-gray);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 0.75rem;
  cursor: pointer;
  color: var(--text-color);
  transition: all 0.2s ease;
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 44px;
  min-height: 44px;
}

.player-btn:hover:not(:disabled) {
  border-color: var(--player-accent);
  color: var(--player-accent);
  background: var(--background-color);
}

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

.player-time {
  margin-left: auto;
  color: var(--player-muted);
  font-size: 0.9rem;
  font-family: 'Courier New', monospace;
  white-space: nowrap;
}

.player-progress {
  display: flex;
  align-items: center;
  width: 100%;
}

.seek-bar {
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: var(--border-color);
  outline: none;
  cursor: pointer;
}

.seek-bar::-webkit-slider-thumb {
  appearance: none;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--player-accent);
  cursor: pointer;
  transition: all 0.2s ease;
}

.seek-bar::-webkit-slider-thumb:hover {
  transform: scale(1.2);
}

.player-extras {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.volume {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.volume-bar {
  width: 80px;
  height: 4px;
}

.speed {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.speed label {
  font-size: 0.9rem;
  color: var(--player-muted);
}

.speed-select {
  padding: 0.25rem 0.5rem;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  background: var(--background-color);
  color: var(--text-color);
  font-size: 0.9rem;
}

/* Mobile responsive */
@media (max-width: 768px) {
  .audio-player {
    flex-direction: column;
    align-items: stretch;
    gap: 1rem;
  }
  
  .player-cover {
    align-self: center;
  }
  
  .player-cover img {
    width: 100px;
    height: 100px;
  }
  
  .player-time {
    margin-left: 0;
    order: -1;
  }
  
  .player-extras {
    justify-content: space-between;
  }
  
  .volume-bar {
    width: 60px;
  }
}

/* Enhanced seek bar styles */
.seek-bar {
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: var(--border-color);
  outline: none;
  cursor: pointer;
  transition: all 0.2s ease;
}

.seek-bar:hover {
  height: 8px;
}

.seek-bar::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--player-accent);
  cursor: pointer;
  transition: all 0.2s ease;
  border: 2px solid #fff;
  box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.seek-bar::-webkit-slider-thumb:hover {
  transform: scale(1.1);
  box-shadow: 0 4px 8px rgba(0,0,0,0.3);
}

.seek-bar::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--player-accent);
  cursor: pointer;
  border: 2px solid #fff;
  box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

/* Prevent text selection during seeking */
.audio-player {
  user-select: none;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
}