/* Design Tokens */
:root {
  /* Colors */
  --color-primary: #2563eb;
  --color-success: #16a34a;
  --color-warning: #ea580c;
  --color-error: #dc2626;
  --color-gray-50: #f9fafb;
  --color-gray-900: #111827;
  --color-white: #ffffff;
  --color-black: #000000;

  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-size-12: 12px;
  --font-size-14: 14px;
  --font-size-16: 16px;
  --font-size-18: 18px;
  --font-size-24: 24px;

  /* Spacing (8px scale) */
  --spacing-8: 8px;
  --spacing-16: 16px;
  --spacing-24: 24px;
  --spacing-48: 48px;

  /* Transitions */
  --transition-duration: 300ms;
  --transition-easing: ease-in-out;
}

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

body {
  font-family: var(--font-family);
  background: var(--color-black);
  color: var(--color-white);
  overflow: hidden;
  width: 100vw;
  height: 100vh;
}

/* Screen States */
.screen {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: none;
  align-items: center;
  justify-content: center;
  flex-direction: column;
}

.screen.active {
  display: flex;
}

/* Loading Screen */
#loading-screen {
  background: var(--color-black);
  text-align: center;
}

.spinner {
  width: 64px;
  height: 64px;
  border: 4px solid rgba(255, 255, 255, 0.1);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin-bottom: var(--spacing-24);
}

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

#loading-message {
  font-size: var(--font-size-18);
  font-weight: 500;
  margin-bottom: var(--spacing-8);
}

#loading-progress {
  font-size: var(--font-size-14);
  color: rgba(255, 255, 255, 0.7);
}

/* Error Screen */
#error-screen {
  background: var(--color-black);
  text-align: center;
  padding: var(--spacing-48);
}

.error-icon {
  width: 64px;
  height: 64px;
  margin-bottom: var(--spacing-24);
}

#error-screen h1 {
  font-size: var(--font-size-24);
  font-weight: 500;
  margin-bottom: var(--spacing-16);
}

#error-message {
  font-size: var(--font-size-14);
  color: rgba(255, 255, 255, 0.8);
  margin-bottom: var(--spacing-24);
  max-width: 500px;
}

.button-group {
  display: flex;
  gap: var(--spacing-16);
  justify-content: center;
}

.btn {
  font-family: var(--font-family);
  font-size: var(--font-size-14);
  font-weight: 500;
  padding: 12px 24px;
  min-height: 48px;
  border-radius: 8px;
  border: none;
  cursor: pointer;
  transition: all var(--transition-duration) var(--transition-easing);
}

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

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

.btn-primary:hover {
  background: #1d4ed8;
}

.btn-primary:disabled {
  background: rgba(37, 99, 235, 0.5);
  cursor: not-allowed;
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.1);
  color: var(--color-white);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.2);
}

.btn-secondary:disabled {
  background: rgba(255, 255, 255, 0.05);
  color: rgba(255, 255, 255, 0.4);
  cursor: not-allowed;
}

/* Player Screen */
#player-screen {
  background: var(--color-black);
  position: relative;
}

.asset {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: contain;
}

/* Offline Badge */
.badge {
  position: absolute;
  top: var(--spacing-16);
  right: var(--spacing-16);
  display: none;
  align-items: center;
  gap: var(--spacing-8);
  padding: 8px 16px;
  background: rgba(0, 0, 0, 0.6);
  border-radius: 16px;
  font-size: var(--font-size-12);
  font-weight: 500;
  color: var(--color-white);
  backdrop-filter: blur(8px);
  animation: fadeIn var(--transition-duration) var(--transition-easing);
  z-index: 100;
}

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

.badge-icon {
  width: 16px;
  height: 16px;
}

/* Transitions (GPU-accelerated) */
@keyframes crossfade {
  from {
    opacity: 0;
    will-change: opacity;
  }
  to {
    opacity: 1;
  }
}

@keyframes fade-to-black {
  0% {
    opacity: 1;
  }
  50% {
    opacity: 0;
  }
  100% {
    opacity: 1;
  }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }

  .spinner {
    animation: none;
    border-top-color: var(--color-primary);
  }
}

/* Mobile Responsive */
@media (max-width: 640px) {
  .badge {
    padding: 6px 12px;
    font-size: 11px;
    top: 12px;
    right: 12px;
  }

  .badge-icon {
    width: 14px;
    height: 14px;
  }

  .btn {
    min-height: 44px;
    padding: 10px 20px;
  }

  #error-screen {
    padding: var(--spacing-24);
  }

  .button-group {
    flex-direction: column;
    width: 100%;
    max-width: 300px;
  }

  .btn {
    width: 100%;
  }
}

/* Accessibility - High Contrast Mode */
@media (prefers-contrast: high) {
  .btn {
    border: 2px solid currentColor;
  }

  .badge {
    border: 1px solid var(--color-white);
  }
}