:root {
  /* Light theme */
  --primary-color: #2563eb;
  --secondary-color: #1e40af;
  --background-color: #f8fafc;
  --text-color: #1e293b;
  --card-bg: #ffffff;
  --border-radius: 12px;
  --transition: all 0.3s ease;
  --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --card-hover-shadow: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --gradient-start: #2563eb;
  --gradient-end: #1e40af;
  --error-bg: #fee2e2;
  --error-text: #dc2626;
  --success-bg: #dcfce7;
  --success-text: #16a34a;
  --input-border: #e2e8f0;
  --input-bg: #ffffff;
  --input-text: #1e293b;
  --input-focus-border: #2563eb;
  --input-focus-shadow: rgba(37, 99, 235, 0.1);
}

[data-theme="dark"] {
  --primary-color: #3b82f6;
  --secondary-color: #60a5fa;
  --background-color: #0f172a;
  --text-color: #e2e8f0;
  --card-bg: #1e293b;
  --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.3), 0 2px 4px -2px rgb(0 0 0 / 0.3);
  --card-hover-shadow: 0 10px 15px -3px rgb(0 0 0 / 0.3), 0 4px 6px -4px rgb(0 0 0 / 0.3);
  --gradient-start: #3b82f6;
  --gradient-end: #60a5fa;
  --error-bg: #7f1d1d;
  --error-text: #fecaca;
  --success-bg: #14532d;
  --success-text: #bbf7d0;
  --input-border: #334155;
  --input-bg: #1e293b;
  --input-text: #e2e8f0;
  --input-focus-border: #3b82f6;
  --input-focus-shadow: rgba(59, 130, 246, 0.1);
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--background-color);
  color: var(--text-color);
  line-height: 1.6;
  transition: background-color 0.3s ease, color 0.3s ease;
}

header {
  background-color: var(--card-bg);
  padding: 1.5rem;
  box-shadow: var(--shadow);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(8px);
  background-color: rgba(var(--card-bg-rgb), 0.9);
  transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

h1 {
  font-size: 2.5rem;
  font-weight: 700;
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 1rem;
  transition: background 0.3s ease;
}

h2 {
  font-size: 1.8rem;
  font-weight: 600;
  margin-bottom: 1rem;
  color: var(--text-color);
  transition: color 0.3s ease;
}

p {
  font-size: 1.1rem;
  color: var(--text-color);
  margin-bottom: 1rem;
  transition: color 0.3s ease;
}

main {
  max-width: 1200px;
  margin: 2rem auto;
  padding: 0 1.5rem;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
}

.content, .about {
  background-color: var(--card-bg);
  padding: 2rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
  transition: var(--transition), background-color 0.3s ease, box-shadow 0.3s ease;
}

.content:hover, .about:hover {
  transform: translateY(-5px);
  box-shadow: var(--card-hover-shadow);
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  padding: 1rem;
}

.video-card {
  background: var(--card-bg);
  border-radius: var(--border-radius);
  overflow: hidden;
  transition: var(--transition), background-color 0.3s ease;
}

.video-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--card-hover-shadow);
}

.video-card h3 {
  font-size: 1.2rem;
  margin: 1rem;
  color: var(--text-color);
  transition: color 0.3s ease;
}

.video-card p {
  font-size: 0.9rem;
  margin: 0 1rem 1rem;
  color: var(--text-color);
  opacity: 0.8;
  transition: color 0.3s ease;
}

iframe {
  width: 100%;
  aspect-ratio: 16/9;
  border-radius: var(--border-radius);
  border: none;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

iframe:hover {
  transform: scale(1.02);
}

.about a {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  background-color: var(--primary-color);
  color: white;
  text-decoration: none;
  border-radius: var(--border-radius);
  margin: 0.5rem 0.5rem 0.5rem 0;
  transition: var(--transition);
  font-weight: 500;
}

.about a:hover {
  background-color: var(--secondary-color);
  transform: translateY(-2px);
}

footer {
  background-color: var(--card-bg);
  padding: 1.5rem;
  text-align: center;
  margin-top: 3rem;
  box-shadow: 0 -4px 6px -1px rgb(0 0 0 / 0.1);
  transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

/* Responsive Design */
@media (max-width: 768px) {
  main {
    grid-template-columns: 1fr;
  }
  
  h1 {
    font-size: 2rem;
  }
  
  .content, .about {
    padding: 1.5rem;
  }

  .theme-toggle {
    bottom: 1rem;
    right: 1rem;
    width: 2.5rem;
    height: 2.5rem;
  }

  .video-grid {
    grid-template-columns: 1fr;
  }

  .toast {
    width: 90%;
    max-width: 400px;
  }
}

/* Animation for page load */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.content, .about {
  animation: fadeIn 0.6s ease-out forwards;
}

.social-links {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  margin-top: 1.5rem;
}

.social-links a {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  background-color: var(--primary-color);
  color: white;
  text-decoration: none;
  border-radius: var(--border-radius);
  transition: var(--transition);
  font-weight: 500;
}

.social-links a:hover {
  background-color: var(--secondary-color);
  transform: translateY(-2px);
}

.social-links a i {
  font-size: 1.2rem;
}

#error-message {
  color: var(--error-text);
  padding: 1rem;
  background-color: var(--error-bg);
  border-radius: var(--border-radius);
  margin-top: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: background-color 0.3s ease, color 0.3s ease;
}

#error-message i {
  font-size: 1.2rem;
}

footer a {
  color: var(--primary-color);
  text-decoration: none;
  transition: var(--transition);
}

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

/* Theme Toggle Button */
.theme-toggle {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  background: var(--card-bg);
  border: none;
  border-radius: 50%;
  width: 3rem;
  height: 3rem;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: var(--shadow);
  transition: var(--transition), background-color 0.3s ease, box-shadow 0.3s ease;
  z-index: 1000;
}

.theme-toggle:hover {
  transform: scale(1.1);
  box-shadow: var(--card-hover-shadow);
}

.theme-toggle i {
  font-size: 1.5rem;
  color: var(--text-color);
  transition: color 0.3s ease;
}

/* Loading Animation */
.loading {
  display: inline-block;
  width: 2rem;
  height: 2rem;
  border: 3px solid var(--primary-color);
  border-radius: 50%;
  border-top-color: transparent;
  animation: spin 1s linear infinite;
}

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

/* Scroll Progress Bar */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(to right, var(--gradient-start), var(--gradient-end));
  transform-origin: 0 50%;
  transform: scaleX(0);
  z-index: 1001;
  transition: background 0.3s ease;
}

/* Card Hover Effects */
.video-card {
  position: relative;
  overflow: hidden;
}

.video-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  opacity: 0;
  transition: var(--transition);
  z-index: 1;
}

.video-card:hover::before {
  opacity: 0.1;
}

/* Improved Button Styles */
.btn {
  position: relative;
  overflow: hidden;
}

.btn::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 50%;
  transform: translate(-50%, -50%);
  transition: width 0.6s, height 0.6s;
}

.btn:hover::after {
  width: 300px;
  height: 300px;
}

/* Toast Notifications */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  padding: 1rem 2rem;
  border-radius: var(--border-radius);
  background: var(--card-bg);
  box-shadow: var(--shadow);
  z-index: 1000;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  animation: slideUp 0.3s ease-out;
  transition: background-color 0.3s ease, box-shadow 0.3s ease;
}

.toast i {
  color: var(--primary-color);
  transition: color 0.3s ease;
}

@keyframes slideUp {
  from {
    transform: translate(-50%, 100%);
    opacity: 0;
  }
  to {
    transform: translate(-50%, 0);
    opacity: 1;
  }
}

/* Print Styles */
@media print {
  .theme-toggle,
  .scroll-progress,
  .toast {
    display: none;
  }

  body {
    background: white;
    color: black;
  }

  .video-card {
    break-inside: avoid;
  }
}

/* Ensure embedded YouTube iframes are always clickable */
.video-card iframe {
  position: relative;
  z-index: 2;
}