#presentation {
  width: 100vw;
  height: 100vh;
  position: relative;
  overflow: hidden;
}

.act {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  padding: var(--space-lg);
  opacity: 0;
  visibility: hidden;
  z-index: var(--z-background);
  background: var(--color-bg-primary);
}

.act--active {
  opacity: 1;
  visibility: visible;
  z-index: var(--z-content);
}

/* Preloader */
#preloader-screen {
  position: fixed;
  inset: 0;
  z-index: var(--z-preloader);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: var(--color-dark-deep);
  gap: var(--space-md);
}

.loader-spinner {
  width: 48px;
  height: 48px;
  border: 3px solid var(--color-gray-700);
  border-top-color: var(--color-accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

.loader-text {
  font-size: var(--size-sm);
  color: var(--color-text-muted);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

/* Progress overlay */
#progress-overlay {
  position: fixed;
  bottom: var(--space-md);
  left: 50%;
  transform: translateX(-50%);
  z-index: var(--z-overlay);
  display: flex;
  gap: var(--space-xs);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--speed-fast), visibility var(--speed-fast);
}

#progress-overlay.visible {
  opacity: 1;
  visibility: visible;
}

.progress-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--color-gray-700);
  transition: background var(--speed-fast);
}

.progress-dot.active {
  background: var(--color-accent);
}

/* Ready indicator - lower right corner */
#ready-indicator {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: var(--z-controls);
  opacity: 0;
  transform: scale(0.8);
  transition: opacity 0.3s ease, transform 0.3s ease;
  pointer-events: none;
}

#ready-indicator.visible {
  opacity: 1;
  transform: scale(1);
}

.ready-indicator__chevron {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: rgba(34, 197, 94, 0.15);
  box-shadow: 0 0 8px rgba(34, 197, 94, 0.2);
  animation: ready-glow 2s ease-in-out infinite;
}

.ready-indicator__chevron::after {
  content: '';
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-success);
}

@keyframes ready-glow {
  0%, 100% { box-shadow: 0 0 6px rgba(34, 197, 94, 0.15); }
  50% { box-shadow: 0 0 12px rgba(34, 197, 94, 0.35); }
}