/*
  Subtle deck navigation.
  Visual navigation is intentionally minimal: two transparent arrows
  overlaid at the bottom-right corner. Keyboard shortcuts remain active:
  ←/→ or PageUp/PageDown for navigation, T for deck/scroll mode,
  F for fullscreen, Home/End for first/last slide.
*/

.deck-nav {
  position: fixed;
  right: clamp(0.8rem, 2vw, 1.5rem);
  bottom: clamp(0.8rem, 2vh, 1.5rem);
  z-index: 5000;

  display: inline-flex;
  align-items: center;
  gap: 0.35rem;

  padding: 0.25rem;
  background: rgba(255, 255, 255, 0.18);
  border: 1px solid rgba(0, 0, 0, 0.08);
  border-radius: 999px;
  backdrop-filter: blur(8px);

  opacity: 0.42;
  transition:
    opacity 160ms ease,
    background 160ms ease,
    border-color 160ms ease;
}

.deck-nav:hover,
.deck-nav:focus-within {
  opacity: 0.92;
  background: rgba(255, 255, 255, 0.72);
  border-color: rgba(0, 0, 0, 0.16);
}

.deck-nav button {
  width: clamp(1.7rem, 2.7vw, 2.25rem);
  height: clamp(1.7rem, 2.7vw, 2.25rem);

  display: inline-flex;
  align-items: center;
  justify-content: center;

  border: 0;
  border-radius: 999px;
  background: transparent;
  color: rgba(0, 0, 0, 0.72);

  font-size: clamp(1rem, 1.7vw, 1.35rem);
  line-height: 1;
  cursor: pointer;

  transition:
    color 160ms ease,
    background 160ms ease,
    transform 120ms ease;
}

.deck-nav button:hover,
.deck-nav button:focus-visible {
  color: var(--epfl-red);
  background: rgba(0, 0, 0, 0.045);
  outline: none;
}

.deck-nav button:active {
  transform: scale(0.94);
}

/* Keep these legacy navigation progress elements harmless if older HTML/JS still contains them. */
.deck-progress,
.deck-progress-bar,
.deck-nav .slide-counter {
  display: none;
}

.slide-number {
  position: absolute;
  left: clamp(0.9rem, 2vw, 1.5rem);
  bottom: clamp(0.85rem, 1.8vh, 1.35rem);
  z-index: 80;

  color: rgba(0, 0, 0, 0.34);
  font-size: clamp(0.65rem, 0.75vw, 0.9rem);
  font-weight: 600;
  letter-spacing: 0.08em;
  line-height: 1;
  font-variant-numeric: tabular-nums;

  pointer-events: none;
  user-select: none;
}

.slide-number::before {
  content: '';
  display: inline-block;
  width: clamp(1.2rem, 2.4vw, 2rem);
  height: 1px;
  margin-right: 0.55rem;
  vertical-align: middle;
  background: rgba(255, 0, 0, 0.45);
}

.title-slide .slide-number {
  color: rgba(0, 0, 0, 0.26);
}

body.mode-scroll .slide-number {
  position: absolute;
}

body.mode-scroll .deck-nav {
  position: fixed;
}