body.ui-style-4 {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body.ui-style-4 header {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

body.ui-style-4 .video-card:hover {
  border-color: #667eea;
}

body.ui-style-4 .quick-link {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

body.ui-style-4 .tag {
  background: #e0e7ff;
  color: #667eea;
}

.back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  background: #667eea;
  color: #fff;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  display: none;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(102, 126, 234, 0.4);
  transition: all 0.3s;
  z-index: 1000;
}

.back-to-top:hover {
  background: #764ba2;
  transform: translateY(-4px);
}

.back-to-top.show {
  display: flex;
}

@media (max-width: 768px) {
  .back-to-top {
    width: 40px;
    height: 40px;
    bottom: 1rem;
    right: 1rem;
  }
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.video-card,
.video-item {
  animation: fadeIn 0.5s ease-out;
}

.section {
  animation: fadeIn 0.6s ease-out;
}

.hero {
  animation: fadeIn 0.4s ease-out;
}

a {
  transition: all 0.3s ease;
}

button,
.quick-link {
  transition: all 0.3s ease;
  cursor: pointer;
}

.video-grid {
  margin-top: 1rem;
}

.info-grid {
  background: linear-gradient(135deg, #f9f9f9 0%, #f0f0f0 100%);
}

h1, h2, h3 {
  letter-spacing: 0.5px;
}

.section h2 {
  position: relative;
  padding-bottom: 0.5rem;
}

.section h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 60px;
  height: 3px;
  background: linear-gradient(90deg, #667eea 0%, transparent 100%);
}

footer {
  background: linear-gradient(135deg, #2d3748 0%, #1a202c 100%);
}

@media (prefers-reduced-motion: reduce) {
  * {
    animation: none !important;
    transition: none !important;
  }
}