.hero {
  position: relative;
  display: flex;
  flex-direction: column;
  min-block-size: clamp(var(--layout-hero-min-height), 100svh, var(--layout-hero-max-height));
  overflow: hidden;
  isolation: isolate;
}

.hero__backdrops,
.hero__frost,
.hero__scrim {
  position: absolute;
  inset: 0;
  z-index: var(--layer-backdrop);
}

/* One slow zoom on the whole stack, so a new painting fades in mid-zoom instead of jumping back. */
.hero__backdrops {
  animation: ken-burns var(--duration-ken-burns) var(--easing-gentle) infinite alternate;
}

.backdrop {
  position: absolute;
  inset: 0;
  opacity: 0;
  transition: opacity var(--duration-crossfade) var(--easing-gentle);
}

.backdrop.is-active {
  opacity: 1;
}

.backdrop--soon {
  background: radial-gradient(
    ellipse at 50% 40%,
    var(--color-soon-glow),
    var(--color-launcher-background) 70%
  );
}

.backdrop__img {
  display: block;
  inline-size: 100%;
  block-size: 100%;
  object-fit: cover;
  image-rendering: pixelated;
}

.backdrop__img.is-smooth {
  image-rendering: auto;
}

/* A blur that fades in toward the bottom, like iOS's progressive blur: the painting stays sharp at
   the top and frosts behind the title and buttons. The mask fades the blur itself, not the art. */
.hero__frost {
  -webkit-backdrop-filter: var(--blur-hero-floor);
  backdrop-filter: var(--blur-hero-floor);
  mask-image: linear-gradient(to bottom, var(--color-clear) 55%, var(--color-black) 80%);
}

.hero__scrim {
  background: linear-gradient(
    to bottom,
    var(--color-scrim-top) 0%,
    var(--color-scrim-middle) 55%,
    var(--color-scrim-low) 78%,
    var(--color-scrim-floor) 100%
  );
}

.hero__content {
  position: relative;
  z-index: var(--layer-content);
  display: flex;
  flex: 1;
  flex-direction: column;
  padding-block: env(safe-area-inset-top) 0;
}

.topbar {
  display: flex;
  gap: var(--space-3);
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4) max(var(--space-gutter), env(safe-area-inset-right)) var(--space-4)
    max(var(--space-gutter), env(safe-area-inset-left));
}

.topbar__actions {
  display: flex;
  gap: var(--space-3);
}

.topbar__title {
  display: flex;
  gap: var(--space-2);
  align-items: center;
  margin: 0;
  font-size: var(--font-size-apple-title-3);
  font-weight: var(--font-weight-bold);
  line-height: var(--leading-apple-title);
  letter-spacing: var(--tracking-brand);
  color: var(--color-on-art);
  text-shadow: var(--text-shadow-on-art);
  transition: color var(--duration-crossfade) var(--easing-gentle);
}

.topbar__logo {
  flex: none;
  inline-size: var(--size-logo);
  block-size: var(--size-logo);
}

#sound-toggle[aria-pressed='true'] .sound-off,
#sound-toggle[aria-pressed='false'] .sound-on {
  display: none;
}

/* The sun and the moon share one spot; the one not showing turns away and shrinks out of sight. */
.appearance-toggle {
  display: inline-grid;
  place-items: center;
}

.appearance-toggle .icon {
  grid-area: 1 / 1;
  transition:
    opacity var(--duration-normal) var(--easing-standard),
    rotate var(--duration-ring) var(--easing-spring),
    scale var(--duration-ring) var(--easing-spring);
}

.appearance-toggle[aria-pressed='true'] .appearance-toggle__sun,
.appearance-toggle[aria-pressed='false'] .appearance-toggle__moon {
  opacity: 0;
  rotate: -90deg;
  scale: 0.5;
}

@media (prefers-reduced-motion: reduce) {
  .appearance-toggle .icon {
    transition: none;
  }
}

.stage {
  display: flex;
  flex: 1;
  flex-direction: column;
  animation: stage-enter var(--duration-enter) var(--easing-spring) backwards;
}

.stage__heading {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  align-items: center;
  padding-block-start: var(--space-1);
}

.stage__prompt {
  margin: 0;
  font-size: var(--font-size-apple-subheadline);
  font-weight: var(--font-weight-semibold);
  letter-spacing: var(--tracking-tight);
  color: var(--color-on-art-secondary);
  text-shadow: var(--text-shadow-on-art);
  transition: color var(--duration-crossfade) var(--easing-gentle);
}

.pager {
  display: flex;
  gap: var(--space-2);
  align-items: center;
  block-size: var(--size-dot);
}

.pager__dot {
  display: block;
  inline-size: var(--size-dot);
  block-size: var(--size-dot);
  background: var(--color-dot);
  border-radius: var(--radius-pill);
  transition:
    inline-size var(--duration-dot) var(--easing-spring),
    background-color var(--duration-dot) var(--easing-standard);
}

.pager__dot.is-active {
  inline-size: var(--size-dot-active);
  background: var(--color-dot-active);
}

@keyframes ken-burns {
  to {
    scale: var(--scale-ken-burns);
  }
}

@keyframes stage-enter {
  from {
    opacity: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  .hero__backdrops,
  .stage {
    animation: none;
  }

  .backdrop,
  .pager__dot {
    transition: none;
  }
}