:root {
  color-scheme: dark;
  --ink: #101827;
  --paper: #fff8ea;
  --paper-soft: #f4e8d0;
  --paper-edge: #d8c099;
  --navy: #08111f;
  --navy-2: #101b32;
  --blue: #6ea8ff;
  --blue-deep: #234d8f;
  --gold: #d6ad63;
  --gold-deep: #936d2f;
  --muted: #a9b6cf;
  --white: #f8fbff;
  --shadow: rgba(0, 0, 0, 0.34);
  --open-progress: 0;
  --letter-progress: 0;
  --takeover-progress: 0;
  --scene-progress: 0;
  --ease-out: cubic-bezier(.2, .75, .16, 1);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--white);
  background:
    radial-gradient(circle at 18% 12%, rgba(110, 168, 255, 0.2), transparent 30rem),
    radial-gradient(circle at 82% 28%, rgba(214, 173, 99, 0.14), transparent 26rem),
    linear-gradient(135deg, #050914 0%, var(--navy) 42%, #11182a 100%);
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: .22;
  background-image:
    linear-gradient(rgba(255,255,255,.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,.03) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(circle at center, black, transparent 78%);
}

.skip-link {
  position: fixed;
  left: 1rem;
  top: 1rem;
  z-index: 20;
  transform: translateY(-150%);
  padding: .75rem 1rem;
  border-radius: 999px;
  color: var(--navy);
  background: var(--paper);
  font-weight: 700;
  text-decoration: none;
  box-shadow: 0 14px 40px var(--shadow);
}

.skip-link:focus {
  transform: translateY(0);
}

.experience {
  position: relative;
}

.intro-copy {
  min-height: 56vh;
  display: grid;
  align-content: end;
  justify-items: center;
  gap: 1rem;
  padding: 8rem 1.5rem 2rem;
  text-align: center;
}

.eyebrow {
  margin: 0;
  color: var(--gold);
  font-size: .78rem;
  font-weight: 800;
  letter-spacing: .18em;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  margin: 0;
  font-family: "Playfair Display", Georgia, serif;
  line-height: 1.02;
}

h1 {
  max-width: 11ch;
  font-size: clamp(3.6rem, 9vw, 8rem);
  letter-spacing: -.06em;
}

.intro-copy__text {
  max-width: 42rem;
  margin: 0;
  color: var(--muted);
  font-size: clamp(1rem, 2vw, 1.25rem);
}

.scroll-stage {
  min-height: 320vh;
  position: relative;
}

.sticky-scene {
  position: sticky;
  top: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  isolation: isolate;
  overflow: hidden;
}

.ambient {
  position: absolute;
  border-radius: 999px;
  filter: blur(4px);
  opacity: calc(.25 + (var(--letter-progress) * .25));
  pointer-events: none;
}

.ambient--one {
  width: 20rem;
  height: 20rem;
  left: 8vw;
  top: 18vh;
  background: radial-gradient(circle, rgba(110,168,255,.34), transparent 66%);
}

.ambient--two {
  width: 26rem;
  height: 26rem;
  right: 2vw;
  bottom: 8vh;
  background: radial-gradient(circle, rgba(214,173,99,.28), transparent 70%);
}

.scene-copy {
  position: absolute;
  top: clamp(1.5rem, 5vw, 4rem);
  left: clamp(1.25rem, 5vw, 5rem);
  z-index: 4;
  display: grid;
  gap: .35rem;
  opacity: calc(1 - var(--takeover-progress));
  transform: translateY(calc(var(--takeover-progress) * -1.5rem));
}

.scene-copy__label {
  color: var(--gold);
  font-size: .75rem;
  font-weight: 800;
  letter-spacing: .18em;
  text-transform: uppercase;
}

.scene-copy__line {
  color: rgba(248,251,255,.9);
  font-size: clamp(1.2rem, 3vw, 2.25rem);
  font-family: "Playfair Display", Georgia, serif;
}

.envelope-system {
  position: relative;
  width: min(78vw, 48rem);
  height: min(58vw, 34rem);
  display: grid;
  place-items: end center;
  perspective: 1300px;
  transform:
    translateY(calc(var(--takeover-progress) * -9rem))
    scale(calc(1 + (var(--letter-progress) * .06) - (var(--takeover-progress) * .1)));
  transition: transform .08s linear;
}

.envelope-system::after {
  content: "";
  position: absolute;
  bottom: 1.2rem;
  width: 72%;
  height: 3rem;
  border-radius: 50%;
  background: radial-gradient(ellipse, rgba(0,0,0,.38), transparent 68%);
  filter: blur(12px);
  transform: scaleX(calc(1 + var(--letter-progress) * .25));
  opacity: calc(.72 - (var(--takeover-progress) * .5));
  z-index: -1;
}

.envelope {
  position: absolute;
  bottom: 2.2rem;
  width: min(88%, 42rem);
  aspect-ratio: 1.72 / 1;
  transform-style: preserve-3d;
  opacity: calc(1 - (var(--takeover-progress) * .76));
  transform: translateY(calc(var(--takeover-progress) * 5rem));
}

.envelope__back,
.envelope__front,
.envelope__pocket,
.envelope__flap,
.envelope__paper-glow {
  position: absolute;
  inset: 0;
  border-radius: 1.1rem;
}

.envelope__back {
  background: linear-gradient(145deg, #e8cf9d, #b9823e 72%);
  box-shadow: 0 26px 65px rgba(0,0,0,.35), inset 0 1px 0 rgba(255,255,255,.38);
}

.envelope__paper-glow {
  inset: 7% 9% 20%;
  background: linear-gradient(180deg, rgba(255,248,234,.45), rgba(255,248,234,0));
  filter: blur(10px);
  opacity: var(--open-progress);
}

.envelope__front {
  top: 34%;
  clip-path: polygon(0 0, 50% 54%, 100% 0, 100% 100%, 0 100%);
  background: linear-gradient(160deg, #deb46e, #b57a35 62%, #8f5e29);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.35);
  z-index: 6;
}

.envelope__pocket {
  top: 34%;
  z-index: 5;
  background: linear-gradient(145deg, #cc934a, #a86e2e);
}

.envelope__pocket--left {
  clip-path: polygon(0 0, 50% 54%, 0 100%);
}

.envelope__pocket--right {
  clip-path: polygon(100% 0, 50% 54%, 100% 100%);
}

.envelope__flap {
  bottom: auto;
  height: 62%;
  transform-origin: 50% 100%;
  transform: rotateX(calc(var(--open-progress) * -168deg));
  clip-path: polygon(0 0, 100% 0, 50% 100%);
  background: linear-gradient(180deg, #f0cf8a, #b9823e 75%);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.48), 0 16px 36px rgba(0,0,0,.24);
  z-index: 11;
  backface-visibility: visible;
}

.envelope__seal {
  position: absolute;
  left: 50%;
  top: 56%;
  z-index: 12;
  width: clamp(3.2rem, 8vw, 4.8rem);
  height: clamp(3.2rem, 8vw, 4.8rem);
  display: grid;
  place-items: center;
  transform: translate(-50%, -50%) scale(calc(1 - var(--open-progress) * .32));
  opacity: calc(1 - var(--open-progress));
  border: 1px solid rgba(255,255,255,.35);
  border-radius: 999px;
  color: #fff4d5;
  background: radial-gradient(circle at 30% 25%, #f0cf8a, #9b672d 72%);
  font-family: "Playfair Display", Georgia, serif;
  font-size: clamp(1.5rem, 4vw, 2.2rem);
  font-weight: 700;
  box-shadow: 0 10px 24px rgba(0,0,0,.28), inset 0 1px 8px rgba(255,255,255,.24);
}

.letter-card {
  width: min(72%, 32rem);
  min-height: min(72vw, 31rem);
  border: 1px solid rgba(216,192,153,.78);
  border-radius: .55rem;
  color: #243047;
  background:
    linear-gradient(90deg, rgba(147,109,47,.08) 1px, transparent 1px) 0 0 / 36px 36px,
    linear-gradient(180deg, var(--paper), #fffdf6 55%, var(--paper-soft));
  box-shadow: 0 28px 70px rgba(0,0,0,.32), inset 0 1px 0 rgba(255,255,255,.8);
}

.letter-card--preview {
  position: absolute;
  bottom: 7.5rem;
  z-index: 4;
  padding: clamp(1.3rem, 3vw, 2.2rem);
  transform:
    translateY(calc(11rem - (var(--letter-progress) * 25rem)))
    rotate(calc((1 - var(--letter-progress)) * -1.4deg));
  opacity: calc(var(--open-progress) * .96);
}

.letter-card__header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.6rem;
}

.letter-card__date {
  color: var(--blue-deep);
  font-size: .72rem;
  font-weight: 800;
  letter-spacing: .15em;
  text-transform: uppercase;
}

.letter-card__rule {
  height: 1px;
  flex: 1;
  background: linear-gradient(90deg, var(--gold), transparent);
}

.letter-card__salute {
  margin: 0 0 1.35rem;
  font-family: "Playfair Display", Georgia, serif;
  font-size: clamp(1.4rem, 3vw, 2.1rem);
}

.letter-lines {
  display: grid;
  gap: .8rem;
}

.letter-lines span {
  height: .55rem;
  border-radius: 999px;
  background: linear-gradient(90deg, rgba(36,48,71,.72), rgba(36,48,71,.16));
}

.letter-lines span:nth-child(2) { width: 88%; }
.letter-lines span:nth-child(3) { width: 94%; }
.letter-lines span:nth-child(4) { width: 62%; }

.letter-card__signature {
  margin: 2rem 0 0;
  color: var(--gold-deep);
  font-family: "Playfair Display", Georgia, serif;
  font-size: 1.5rem;
}

.scroll-hint {
  position: absolute;
  bottom: clamp(1rem, 4vh, 2.25rem);
  display: inline-flex;
  align-items: center;
  gap: .7rem;
  color: rgba(248,251,255,.72);
  font-size: .84rem;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  opacity: calc(1 - var(--letter-progress));
}

.scroll-hint__mouse {
  width: 1.45rem;
  height: 2.15rem;
  border: 1px solid rgba(248,251,255,.55);
  border-radius: 999px;
  position: relative;
}

.scroll-hint__mouse::after {
  content: "";
  position: absolute;
  left: 50%;
  top: .38rem;
  width: .28rem;
  height: .28rem;
  border-radius: 999px;
  background: var(--gold);
  transform: translateX(-50%);
  animation: mouse-dot 1.55s var(--ease-out) infinite;
}

@keyframes mouse-dot {
  0% { transform: translate(-50%, 0); opacity: 0; }
  30% { opacity: 1; }
  100% { transform: translate(-50%, .7rem); opacity: 0; }
}

.letter-section {
  position: relative;
  z-index: 3;
  margin-top: -26vh;
  padding: 0 1.25rem 8rem;
}

.letter-document {
  width: min(100%, 54rem);
  margin: 0 auto;
  padding: clamp(2rem, 6vw, 5rem);
  border: 1px solid rgba(216,192,153,.74);
  border-radius: 1.4rem;
  color: var(--ink);
  background:
    linear-gradient(90deg, rgba(147,109,47,.06) 1px, transparent 1px) 0 0 / 44px 44px,
    linear-gradient(180deg, #fffaf0, #fffdf8 36%, #f4ead7);
  box-shadow: 0 34px 90px rgba(0,0,0,.38), inset 0 1px 0 rgba(255,255,255,.9);
  transform: translateY(calc((1 - var(--takeover-progress)) * 4rem));
  opacity: calc(.35 + (var(--takeover-progress) * .65));
}

.letter-document__masthead {
  padding-bottom: 2.2rem;
  border-bottom: 1px solid rgba(147,109,47,.22);
}

.letter-document h2 {
  margin-top: .7rem;
  color: #14213c;
  font-size: clamp(2.3rem, 7vw, 5.4rem);
  letter-spacing: -.045em;
}

.letter-document__lede {
  max-width: 42rem;
  color: #4d5a6f;
  font-size: clamp(1rem, 2vw, 1.18rem);
  line-height: 1.8;
}

.letter-section-block {
  position: relative;
  display: grid;
  gap: .85rem;
  padding: 2rem 0 0 4.2rem;
}

.section-number {
  position: absolute;
  left: 0;
  top: 2rem;
  width: 2.8rem;
  height: 2.8rem;
  display: grid;
  place-items: center;
  border: 1px solid rgba(35,77,143,.18);
  border-radius: 999px;
  color: var(--blue-deep);
  background: rgba(110,168,255,.1);
  font-size: .78rem;
  font-weight: 800;
}

.letter-section-block h3 {
  color: #17233a;
  font-size: clamp(1.55rem, 3vw, 2.2rem);
}

.letter-section-block p,
.letter-document__footer p {
  margin: 0;
  color: #39465d;
  font-size: 1.02rem;
  line-height: 1.82;
}

.letter-document__footer {
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid rgba(147,109,47,.22);
}

.letter-document__footer strong {
  display: block;
  margin-top: .35rem;
  color: #17233a;
  font-family: "Playfair Display", Georgia, serif;
  font-size: 2rem;
}

.noscript-note {
  margin: 1rem;
  padding: 1rem;
  border-radius: .75rem;
  color: var(--navy);
  background: var(--paper);
}

@media (max-width: 720px) {
  .intro-copy {
    min-height: 48vh;
    padding-top: 5rem;
  }

  .scroll-stage {
    min-height: 260vh;
  }

  .scene-copy {
    right: 1.25rem;
    text-align: center;
  }

  .envelope-system {
    width: 96vw;
    height: 74vw;
  }

  .letter-card--preview {
    width: 78%;
    bottom: 5.8rem;
    min-height: 24rem;
    transform: translateY(calc(8rem - (var(--letter-progress) * 19rem)));
  }

  .envelope {
    bottom: 1.6rem;
    width: 92%;
  }

  .letter-section {
    margin-top: -14vh;
  }

  .letter-document {
    padding: 1.6rem;
    border-radius: 1rem;
  }

  .letter-section-block {
    padding-left: 0;
  }

  .section-number {
    position: static;
  }
}

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

  *,
  *::before,
  *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }

  :root {
    --open-progress: 1;
    --letter-progress: 1;
    --takeover-progress: 1;
    --scene-progress: 1;
  }

  .scroll-stage {
    min-height: 110vh;
  }

  .sticky-scene {
    position: relative;
  }

  .letter-section {
    margin-top: 0;
  }
}