frontend/src/css/responsive/performance/lazy-loading.css

/* Lazy Loading Performance Optimizations */

/* Image Lazy Loading */
.lazy-image {
  opacity: 0;
  transition: opacity 0.3s ease;
  background-color: #f0f0f0;
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
}

.lazy-image.loaded {
  opacity: 1;
}

.lazy-image.loading {
  background-image: url('data:image/svg+xml;base64,PHN2ZyB3aWR0aD0iMjAwIiBoZWlnaHQ9IjIwMCIgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIj48cmVjdCB3aWR0aD0iMjAwIiBoZWlnaHQ9IjIwMCIgZmlsbD0iI2YwZjBmMCIvPjx0ZXh0IHg9IjUwJSIgeT0iNTAlIiBkeD0iMCUiZmlsbD0idXJsKCNjMDAwMDAwKSIgZm9udC1zaXplPSIxNCIgZmlsbD0iIzMzMzMzMyIgdGV4dC1hbmNob3I9Im1pZGRsZSIgZHk9Ii4zZW0iPuaIkOWbvueJhzwvdGV4dD48L3N2Zz4=');
}

.lazy-image.error {
  background-image: url('data:image/svg+xml;base64,PHN2ZyB3aWR0aD0iMjAwIiBoZWlnaHQ9IjIwMCIgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIj48cmVjdCB3aWR0aD0iMjAwIiBoZWlnaHQ9IjIwMCIgZmlsbD0iI2ZmZiIvPjx0ZXh0IHg9IjUwJSIgeT0iNTAlIiBkeD0iMCUiZmlsbD0idXJsKCNjMDAwMDAwKSIgZm9udC1zaXplPSIxNCIgZmlsbD0iIzMzMzMzMyIgdGV4dC1hbmNob3I9Im1pZGRsZSIgZHk9Ii4zZW0iPlVubGljZS1EZXNjcmlwdGlvbi1BZHZhbmNlZCAtLTwvdGV4dD48L3N2Zz4=');
}

/* Component Lazy Loading */
.lazy-component {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.3s ease, transform 0.3s ease;
}

.lazy-component.loaded {
  opacity: 1;
  transform: translateY(0);
}

.lazy-component.loading {
  min-height: 200px;
  background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
  background-size: 200% 100%;
  animation: lazyLoading 1.5s infinite;
}

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

/* Background Lazy Loading */
.lazy-background {
  background-color: #f8f9fa;
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  transition: background-image 0.3s ease;
}

.lazy-background.loaded {
  background-image: var(--lazy-bg-image);
}

/* Video Lazy Loading */
.lazy-video {
  opacity: 0;
  transition: opacity 0.3s ease;
}

.lazy-video.loaded {
  opacity: 1;
}

.lazy-video video {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* Iframe Lazy Loading */
.lazy-iframe {
  opacity: 0;
  transition: opacity 0.3s ease;
}

.lazy-iframe.loaded {
  opacity: 1;
}

.lazy-iframe iframe {
  width: 100%;
  height: 100%;
  border: none;
}

/* Intersection Observer Fallback */
.no-intersection-observer .lazy-image,
.no-intersection-observer .lazy-component,
.no-intersection-observer .lazy-background,
.no-intersection-observer .lazy-video,
.no-intersection-observer .lazy-iframe {
  opacity: 1;
  transform: none;
}

/* Loading States */
.loading-skeleton {
  background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
  background-size: 200% 100%;
  animation: loadingSkeleton 1.5s infinite;
}

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

.loading-pulse {
  animation: loadingPulse 1.5s ease-in-out infinite;
}

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

.loading-spinner {
  border: 3px solid #f3f3f3;
  border-top: 3px solid var(--primary-color);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  animation: loadingSpin 1s linear infinite;
}

@keyframes loadingSpin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}

/* Progressive Image Loading */
.progressive-image {
  opacity: 0;
  transition: opacity 0.3s ease;
}

.progressive-image.loaded-low {
  opacity: 0.5;
}

.progressive-image.loaded-high {
  opacity: 1;
}

/* Placeholder Images */
.placeholder-avatar {
  background: linear-gradient(45deg, #e0e0e0 25%, #f0f0f0 50%, #e0e0e0 75%);
  background-size: 200% 200%;
  animation: placeholderAnimation 1.5s ease infinite;
}

@keyframes placeholderAnimation {
  0% {
    background-position: 0% 50%;
  }
  50% {
    background-position: 100% 50%;
  }
  100% {
    background-position: 0% 50%;
  }
}

.placeholder-card {
  background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
  background-size: 200% 100%;
  animation: placeholderAnimation 1.5s ease infinite;
}

/* Error States */
.error-state {
  background: #fff5f5;
  border: 1px solid #fed7d7;
  border-radius: 8px;
  padding: 16px;
  text-align: center;
  color: #c53030;
}

.error-state svg {
  width: 48px;
  height: 48px;
  margin-bottom: 8px;
  color: #c53030;
}

/* Retry Button */
.retry-button {
  background: var(--primary-color);
  color: white;
  border: none;
  padding: 8px 16px;
  border-radius: 4px;
  cursor: pointer;
  font-size: 14px;
  margin-top: 8px;
  transition: background 0.2s ease;
}

.retry-button:hover {
  background: var(--primary-color-dark);
}

.retry-button:focus {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}

/* Performance Metrics */
.performance-indicator {
  position: fixed;
  top: 10px;
  right: 10px;
  background: rgba(0, 0, 0, 0.8);
  color: white;
  padding: 8px 12px;
  border-radius: 4px;
  font-size: 12px;
  font-family: monospace;
  z-index: 9999;
}

.performance-indicator.good {
  background: rgba(34, 197, 94, 0.8);
}

.performance-indicator.warning {
  background: rgba(251, 191, 36, 0.8);
}

.performance-indicator.poor {
  background: rgba(239, 68, 68, 0.8);
}

/* Lazy Loading Thresholds */
.lazy-load-threshold-0 {
  opacity: 0;
  transition: opacity 0.3s ease;
}

.lazy-load-threshold-0.loaded {
  opacity: 1;
}

.lazy-load-threshold-100 {
  opacity: 0;
  transition: opacity 0.3s ease;
}

.lazy-load-threshold-100.loaded {
  opacity: 1;
}

.lazy-load-threshold-200 {
  opacity: 0;
  transition: opacity 0.3s ease;
}

.lazy-load-threshold-200.loaded {
  opacity: 1;
}

.lazy-load-threshold-300 {
  opacity: 0;
  transition: opacity 0.3s ease;
}

.lazy-load-threshold-300.loaded {
  opacity: 1;
}

/* Mobile Lazy Loading */
@media (max-width: 767px) {
  .mobile-lazy-image {
    opacity: 0;
    transition: opacity 0.5s ease;
  }
  
  .mobile-lazy-image.loaded {
    opacity: 1;
  }
  
  .mobile-lazy-component {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.5s ease, transform 0.5s ease;
  }
  
  .mobile-lazy-component.loaded {
    opacity: 1;
    transform: translateY(0);
  }
}

/* High DPI Lazy Loading */
@media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi) {
  .lazy-image.high-dpi {
    image-rendering: -webkit-optimize-contrast;
    image-rendering: crisp-edges;
  }
}

/* Low Data Mode Lazy Loading */
@media (prefers-reduced-data: reduce) {
  .lazy-image.low-data {
    display: none;
  }
  
  .lazy-placeholder.low-data {
    display: block;
  }
}

/* Reduced Motion Lazy Loading */
@media (prefers-reduced-motion: reduce) {
  .lazy-image,
  .lazy-component,
  .lazy-background,
  .lazy-video,
  .lazy-iframe {
    transition: none;
  }
  
  .loading-skeleton,
  .loading-pulse,
  .placeholder-avatar,
  .placeholder-card {
    animation: none;
  }
}

/* Print Mode Lazy Loading */
@media print {
  .lazy-image,
  .lazy-video,
  .lazy-iframe {
    opacity: 1 !important;
    transform: none !important;
  }
  
  .loading-skeleton,
  .loading-pulse,
  .loading-spinner {
    display: none !important;
  }
}