*,
*::before,
*::after {
  box-sizing: border-box;
}

:root {
  color-scheme: dark;
  --page-bg: #000;
  --text-primary: rgba(255, 255, 255, 0.98);
  --text-secondary: rgba(255, 255, 255, 0.76);
  --cta-bg: rgba(19, 19, 20, 0.4);
  --cta-border: rgba(255, 255, 255, 0.08);
  --shadow-soft: 0 20px 60px rgba(0, 0, 0, 0.28);
}

html {
  scroll-behavior: smooth;
  scroll-snap-type: y mandatory;
  background: var(--page-bg);
}

body {
  margin: 0;
  min-height: 100svh;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "SF Pro Text", sans-serif;
  background: var(--page-bg);
  color: var(--text-primary);
}

img {
  display: block;
  max-width: 100%;
}

a {
  color: inherit;
  text-decoration: none;
}

.app {
  position: relative;
}

.screen {
  --content-width: min(88vw, 42rem);
  --text-top: 46%;
  --text-align: center;
  --title-max: 17ch;
  --subtitle-max: 30ch;
  --bg-position-portrait: 50% 50%;
  --bg-position-landscape: 50% 50%;
  --overlay-opacity: 0.44;
  --vignette-opacity: 0.88;
  --focus-x: 50%;
  --focus-y: 48%;
  --bird-main-width: min(48vw, 30rem);
  --bird-main-left: 50%;
  --bird-main-top: 63%;
  --bird-main-rotate: 0deg;
  --bird-secondary-width: min(22vw, 12rem);
  --bird-secondary-left: 20%;
  --bird-secondary-top: 64%;
  --ambient-bird-width: min(16vw, 10rem);
  --ambient-bird-left: 76%;
  --ambient-bird-top: 18%;
  --card-main-width: min(54vw, 24rem);
  --card-main-left: 50%;
  --card-main-top: 72%;
  --card-left-width: min(30vw, 15rem);
  --card-left-left: 26%;
  --card-left-top: 74%;
  --card-right-width: min(30vw, 15rem);
  --card-right-left: 74%;
  --card-right-top: 74%;
  --ui-audio-panel-width: min(60vw, 22rem);
  --ui-audio-panel-left: 50%;
  --ui-audio-panel-top: 62%;
  --stats-panel-width: min(62vw, 24rem);
  --stats-panel-left: 50%;
  --stats-panel-top: 70%;
  --grave-foreground-width: min(76vw, 34rem);
  --grave-foreground-left: 50%;
  --grave-foreground-top: 84%;
  position: relative;
  min-height: 100svh;
  overflow: hidden;
  scroll-snap-align: start;
  isolation: isolate;
  background:
    radial-gradient(circle at var(--focus-x) var(--focus-y), rgba(44, 48, 54, 0.22), transparent 42%),
    linear-gradient(180deg, #090909 0%, #040404 58%, #000 100%);
}

.screen::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at var(--focus-x) var(--focus-y), transparent 0%, rgba(0, 0, 0, calc(var(--vignette-opacity) * 0.36)) 52%, rgba(0, 0, 0, var(--vignette-opacity)) 100%),
    linear-gradient(180deg, rgba(0, 0, 0, calc(var(--overlay-opacity) * 0.56)) 0%, rgba(0, 0, 0, var(--overlay-opacity)) 42%, rgba(0, 0, 0, calc(var(--overlay-opacity) * 1.24)) 100%);
  z-index: 1;
  pointer-events: none;
}

.screen-bg,
.screen-overlay,
.screen-foreground,
.screen-visuals {
  position: absolute;
  inset: 0;
}

.screen-bg {
  z-index: 0;
}

.screen-bg-layer {
  position: absolute;
  inset: 0;
  opacity: 0;
  background-repeat: no-repeat;
  background-size: cover;
  transition: opacity 500ms ease;
}

.screen-bg-layer.is-visible {
  opacity: 1;
}

.screen-bg-portrait {
  background-position: var(--bg-position-portrait);
}

.screen-bg-landscape {
  display: none;
  background-position: var(--bg-position-landscape);
}

.screen-overlay {
  z-index: 1;
  pointer-events: none;
}

.screen-foreground {
  z-index: 2;
}

.screen-text {
  position: absolute;
  left: 50%;
  top: var(--text-top);
  z-index: 4;
  width: var(--content-width);
  max-width: calc(100vw - 2.5rem);
  transform: translate(-50%, -50%);
  text-align: var(--text-align);
  opacity: 0;
  transition:
    opacity 700ms ease,
    transform 900ms cubic-bezier(0.22, 1, 0.36, 1);
}

.screen.is-visible .screen-text {
  opacity: 1;
  transform: translate(-50%, calc(-50% - 0.5rem));
}

.screen-text h1,
.screen-text p {
  margin: 0;
  text-wrap: balance;
}

.screen-text h1 {
  max-width: var(--title-max);
  margin-inline: auto;
  font-size: clamp(2.2rem, 5vw, 4.5rem);
  font-weight: 700;
  line-height: 0.96;
  letter-spacing: -0.04em;
  text-shadow: 0 10px 28px rgba(0, 0, 0, 0.25);
}

.screen-text p {
  max-width: var(--subtitle-max);
  margin: 0.95rem auto 0;
  font-size: clamp(1rem, 2vw, 1.5rem);
  font-weight: 500;
  line-height: 1.35;
  color: var(--text-secondary);
  text-shadow: 0 8px 22px rgba(0, 0, 0, 0.22);
}

.screen-visuals {
  z-index: 3;
  pointer-events: none;
}

.visual {
  position: absolute;
  left: 50%;
  top: 50%;
  opacity: 0;
  transform: translate(-50%, -50%) scale(0.985);
  transition:
    opacity 850ms ease,
    transform 1100ms cubic-bezier(0.22, 1, 0.36, 1);
  filter: drop-shadow(0 24px 55px rgba(0, 0, 0, 0.34));
  will-change: transform;
}

.screen.is-visible .visual.is-ready {
  opacity: 1;
}

.screen.is-visible .visual.is-ready.visual-bird-main {
  transform: translate(-50%, -50%) rotate(var(--bird-main-rotate));
}

.screen.is-visible .visual.is-ready:not(.visual-bird-main) {
  transform: translate(-50%, -50%);
}

.visual-bird-main {
  width: var(--bird-main-width);
  left: var(--bird-main-left);
  top: var(--bird-main-top);
  z-index: 5;
}

.visual-bird-secondary {
  width: var(--bird-secondary-width);
  left: var(--bird-secondary-left);
  top: var(--bird-secondary-top);
  z-index: 4;
  opacity: 0.82;
}

.visual-ambient-bird {
  width: var(--ambient-bird-width);
  left: var(--ambient-bird-left);
  top: var(--ambient-bird-top);
  z-index: 2;
  opacity: 0.28;
}

.visual-card-main {
  width: var(--card-main-width);
  left: var(--card-main-left);
  top: var(--card-main-top);
  z-index: 5;
}

.visual-card-left {
  width: var(--card-left-width);
  left: var(--card-left-left);
  top: var(--card-left-top);
  z-index: 4;
}

.visual-card-right {
  width: var(--card-right-width);
  left: var(--card-right-left);
  top: var(--card-right-top);
  z-index: 4;
}

.visual-ui-audio-panel {
  width: var(--ui-audio-panel-width);
  left: var(--ui-audio-panel-left);
  top: var(--ui-audio-panel-top);
  z-index: 4;
}

.visual-stats-panel {
  width: var(--stats-panel-width);
  left: var(--stats-panel-left);
  top: var(--stats-panel-top);
  z-index: 4;
}

.visual-grave-foreground {
  width: var(--grave-foreground-width);
  left: var(--grave-foreground-left);
  top: var(--grave-foreground-top);
  z-index: 3;
  filter: drop-shadow(0 12px 34px rgba(0, 0, 0, 0.28));
}

.visual.is-hidden {
  display: none;
}

.app-store-cta {
  position: fixed;
  left: 50%;
  bottom: max(1.25rem, env(safe-area-inset-bottom));
  z-index: 12;
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: 0.35rem;
  padding: 0.5rem 0.55rem;
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 1rem;
  background: rgba(16, 16, 18, 0.26);
  backdrop-filter: blur(16px) saturate(115%);
  -webkit-backdrop-filter: blur(16px) saturate(115%);
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.22);
  transform: translateX(-50%);
}

.app-store-label {
  font-size: 0.68rem;
  font-weight: 500;
  letter-spacing: 0.015em;
  color: rgba(255, 255, 255, 0.68);
}

.app-store-badge-image {
  display: block;
  height: 2.25rem;
  width: auto;
}

.screen-1 {
  --text-top: 39%;
  --focus-y: 42%;
  --bird-main-top: 71%;
  --bird-main-left: 50%;
  --bird-main-width: min(52vw, 34rem);
  --ambient-bird-top: 23%;
  --ambient-bird-left: 76%;
}

.screen-2 {
  --text-top: 40%;
  --focus-x: 48%;
  --focus-y: 46%;
  --bird-main-top: 75%;
  --bird-main-left: 45%;
  --bird-main-width: min(46vw, 28rem);
  --bird-secondary-top: 65%;
  --bird-secondary-left: 26%;
}

.screen-3 {
  --text-top: 30%;
  --focus-y: 56%;
  --card-main-top: 70%;
  --card-main-width: min(58vw, 25rem);
  --card-left-top: 72%;
  --card-right-top: 72%;
  --bird-main-top: 70%;
  --bird-main-left: 50%;
  --bird-main-width: min(30vw, 18rem);
}

.screen-4 {
  --text-top: 48%;
  --focus-y: 50%;
  --ui-audio-panel-top: 63%;
  --bird-main-top: 79%;
  --bird-main-left: 55%;
  --bird-main-width: min(42vw, 24rem);
}

.screen-5 {
  --text-top: 32%;
  --focus-y: 56%;
  --stats-panel-top: 68%;
  --card-main-top: 73%;
  --bird-main-top: 82%;
  --bird-main-left: 46%;
  --bird-main-width: min(30vw, 16rem);
}

.screen-6 {
  --text-top: 31%;
  --focus-y: 54%;
  --card-main-top: 68%;
  --card-main-width: min(50vw, 22rem);
  --grave-foreground-top: 86%;
  --grave-foreground-width: min(86vw, 40rem);
}

@media (min-width: 820px) {
  .screen {
    --content-width: min(60vw, 48rem);
  }

  .screen-bg-portrait {
    display: none;
  }

  .screen-bg-landscape {
    display: block;
  }

  .screen-text {
    max-width: calc(100vw - 6rem);
  }

  .screen-1 {
    --text-top: 42%;
    --bird-main-top: 74%;
    --bird-main-left: 52%;
    --bird-main-width: min(30vw, 31rem);
  }

  .screen-2 {
    --bird-main-left: 45%;
    --bird-main-top: 76%;
    --bird-main-width: min(26vw, 24rem);
    --bird-secondary-left: 36%;
    --bird-secondary-top: 68%;
    --bird-secondary-width: min(14vw, 12rem);
  }

  .screen-3 {
    --content-width: min(50vw, 34rem);
    --text-top: 33%;
    --card-main-width: min(26vw, 25rem);
    --card-left-width: min(16vw, 15rem);
    --card-right-width: min(16vw, 15rem);
    --card-left-left: 36%;
    --card-main-left: 50%;
    --card-right-left: 64%;
  }

  .screen-4 {
    --text-top: 44%;
    --ui-audio-panel-width: min(24vw, 24rem);
    --ui-audio-panel-top: 62%;
    --bird-main-width: min(24vw, 20rem);
    --bird-main-top: 74%;
  }

  .screen-5 {
    --content-width: min(46vw, 34rem);
    --text-top: 34%;
    --stats-panel-width: min(30vw, 28rem);
    --card-main-width: min(20vw, 16rem);
    --card-main-left: 47%;
    --bird-main-left: 50%;
    --bird-main-top: 74%;
    --bird-main-width: min(20vw, 16rem);
  }

  .screen-6 {
    --content-width: min(46vw, 34rem);
    --text-top: 34%;
    --card-main-top: 70%;
    --card-main-width: min(24vw, 20rem);
    --grave-foreground-width: min(60vw, 46rem);
  }

  .app-store-cta {
    left: auto;
    right: max(1.5rem, env(safe-area-inset-right));
    bottom: max(1.5rem, env(safe-area-inset-bottom));
    transform: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .screen-text,
  .visual,
  .screen-bg-layer {
    transition: none;
  }
}