:root {
  --abyss: #0a1a2f;
  --trench: #0f2847;
  --pressure: #163a5e;
  --foam: #8fa8c2;
  --repair: #c8956a;
  --oxidation: #7a5c42;
  --salt: #d4d8dc;
  --crack-angle-a: 7deg;
  --crack-angle-b: -12deg;
  --crack-angle-c: 3deg;
}

/* Implementation note: IntersectionObserver` combined with a passive scroll listener that applies `transform` values to elements with `will-change: transform`. */

* { box-sizing: border-box; }

html {
  background: var(--abyss);
  color: var(--foam);
  font-family: "Nunito Sans", Inter, sans-serif;
}

body {
  margin: 0;
  min-height: 500vh;
  overflow-x: hidden;
  background:
    radial-gradient(ellipse at 18% 8%, rgba(22, 58, 94, 0.7), transparent 38vw),
    linear-gradient(180deg, #163a5e 0%, #0f2847 19%, #0a1a2f 54%, #06111f 100%);
}

.grain {
  position: fixed;
  inset: 0;
  z-index: 90;
  pointer-events: none;
  opacity: 0.16;
  mix-blend-mode: overlay;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='90' height='90' viewBox='0 0 90 90'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.72' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='90' height='90' filter='url(%23n)' opacity='.42'/%3E%3C/svg%3E");
}

.depth-progress {
  position: fixed;
  z-index: 100;
  left: 22px;
  top: 12vh;
  width: 24px;
  height: 76vh;
}

.progress-line {
  position: absolute;
  left: 11px;
  top: 0;
  bottom: 0;
  width: 1px;
  background: rgba(143, 168, 194, 0.25);
}

.progress-line span {
  display: block;
  width: 1px;
  height: 0%;
  background: var(--repair);
  box-shadow: 0 0 18px rgba(200, 149, 106, 0.55);
}

.depth-mark {
  position: absolute;
  left: 0;
  width: 24px;
  height: 24px;
  fill: var(--abyss);
  stroke: rgba(143, 168, 194, 0.5);
  stroke-width: 1.2;
  transition: stroke 0.35s ease, filter 0.35s ease, transform 0.35s ease;
}

.depth-mark:nth-of-type(1) { top: -10px; }
.depth-mark:nth-of-type(2) { top: 31%; transform: rotate(-9deg); }
.depth-mark:nth-of-type(3) { top: 63%; transform: rotate(6deg); }
.depth-mark:nth-of-type(4) { bottom: -10px; transform: rotate(-3deg); }

.depth-mark.active {
  stroke: var(--repair);
  filter: drop-shadow(0 0 8px rgba(200, 149, 106, 0.9));
}

.descent {
  position: relative;
  min-height: 500vh;
  perspective: 900px;
  transform-style: preserve-3d;
}

.layer {
  position: relative;
  min-height: 125vh;
  transform-style: preserve-3d;
  padding: 14vh 8vw 20vh 12vw;
}

.surface-layer {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 0;
  overflow: hidden;
}

.photo-plane {
  position: absolute;
  pointer-events: none;
  filter: contrast(1.1) saturate(0.7) brightness(0.8);
  opacity: 0.9;
  will-change: transform;
}

.ocean-surface {
  inset: -12vh -8vw;
  background:
    linear-gradient(rgba(10, 26, 47, 0.18), rgba(10, 26, 47, 0.84)),
    radial-gradient(ellipse at 47% 28%, rgba(212, 216, 220, 0.2), transparent 18%),
    radial-gradient(ellipse at 70% 42%, rgba(143, 168, 194, 0.15), transparent 32%),
    repeating-linear-gradient(172deg, rgba(212,216,220,.12) 0 1px, transparent 1px 13px),
    linear-gradient(141deg, #1a4669, #0f2847 38%, #0a1a2f 86%);
}

.rock-document {
  width: 38vw;
  height: 54vh;
  right: 5vw;
  top: 18vh;
  clip-path: polygon(1% 0, 98% 2%, 100% 96%, 3% 100%);
  background:
    radial-gradient(circle at 35% 24%, rgba(212,216,220,.18), transparent 8%),
    radial-gradient(circle at 60% 52%, rgba(122,92,66,.28), transparent 24%),
    repeating-linear-gradient(105deg, rgba(212,216,220,.05) 0 2px, transparent 2px 18px),
    linear-gradient(135deg, #20374d, #0a1a2f 68%);
}

.hull-document {
  width: 32vw;
  height: 38vh;
  left: 18vw;
  bottom: 12vh;
  clip-path: polygon(3% 4%, 100% 0, 97% 100%, 0 94%);
  opacity: 0.55;
  background:
    repeating-linear-gradient(6deg, rgba(122,92,66,.24) 0 5px, transparent 5px 22px),
    radial-gradient(ellipse at 30% 60%, rgba(200,149,106,.12), transparent 28%),
    linear-gradient(90deg, #102339, #163a5e, #081525);
}

.depth-fog {
  position: fixed;
  inset: -20vh -20vw;
  pointer-events: none;
  z-index: 2;
  opacity: 0.48;
  background: radial-gradient(ellipse at 50% 50%, rgba(15, 40, 71, 0.6), transparent 58%);
  will-change: transform, opacity;
}

.hero-stamp {
  position: relative;
  z-index: 4;
  transform: translateZ(80px) rotate(-2deg);
  margin-left: -10vw;
  will-change: transform;
}

h1, h2, p { margin: 0; }

h1 {
  font-family: "Nunito", sans-serif;
  font-size: clamp(3rem, 8vw, 6.5rem);
  letter-spacing: 0.02em;
  line-height: 0.9;
  color: var(--salt);
  text-shadow: 0 3px 0 rgba(10, 26, 47, 0.8), 0 0 38px rgba(143, 168, 194, 0.18);
}

h2 {
  font-family: "Nunito", sans-serif;
  font-size: clamp(2rem, 5vw, 4.8rem);
  line-height: 0.96;
  letter-spacing: -0.025em;
  color: var(--salt);
}

p {
  color: var(--foam);
  font-size: clamp(0.95rem, 1.1vw, 1.15rem);
  line-height: 1.75;
}

.annotation,
.margin-note {
  font-family: "Caveat", cursive;
  font-size: 0.95rem;
  line-height: 1.25;
  color: var(--repair);
  letter-spacing: 0.02em;
}

.shard-panel,
.bed-thought {
  position: relative;
  z-index: 6;
  display: grid;
  grid-template-columns: minmax(210px, 0.86fr) minmax(260px, 1.14fr);
  gap: 8px;
  max-width: 920px;
  margin: 0;
  transform-style: preserve-3d;
  will-change: transform;
}

.fragment {
  position: relative;
  min-height: 260px;
  padding: clamp(1.4rem, 3.4vw, 3.2rem);
  background: rgba(10, 26, 47, 0.85);
  border: 1px solid rgba(122, 92, 66, 0.55);
  box-shadow: 0 28px 70px rgba(0, 0, 0, 0.32), inset 0 0 40px rgba(143, 168, 194, 0.03);
  backdrop-filter: blur(5px);
  overflow: hidden;
}

.fragment::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: 0.03;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='44' height='44' viewBox='0 0 44 44'%3E%3Cg fill='%23d4d8dc'%3E%3Ccircle cx='8' cy='9' r='1.1'/%3E%3Ccircle cx='28' cy='14' r='.8'/%3E%3Ccircle cx='18' cy='31' r='1.4'/%3E%3Ccircle cx='39' cy='35' r='.7'/%3E%3C/g%3E%3C/svg%3E");
}

.fragment-left { clip-path: polygon(0.5% 0%, 98.6% 1.5%, 100% 99.3%, 1.8% 98.8%); }
.fragment-right { clip-path: polygon(1.8% 1.2%, 99.2% 0.8%, 98.7% 99.2%, 0.3% 99.7%); }

.fragment-left > *, .fragment-right > * { position: relative; z-index: 2; }

.repair-seam {
  position: absolute;
  left: -6px;
  top: 8%;
  width: 2px;
  height: 84%;
  background: var(--repair);
  opacity: 0;
  box-shadow: 0 0 18px rgba(200, 149, 106, 0.7);
  transform: rotate(3deg) scaleY(0.72);
  transition: opacity 1.2s cubic-bezier(0.25, 0.1, 0.25, 1), transform 1.2s cubic-bezier(0.25, 0.1, 0.25, 1);
}

.reveal-panel .fragment-left { transform: translateX(-8px) translateY(6px); }
.reveal-panel .fragment-right { transform: translateX(8px) translateY(-6px); }
.reveal-panel .fragment { transition: transform 1.2s cubic-bezier(0.25, 0.1, 0.25, 1); }
.reveal-panel.repaired .fragment { transform: translateX(0) translateY(0); }
.reveal-panel.repaired .repair-seam { opacity: 1; transform: rotate(3deg) scaleY(1); }

.panel-one { margin-left: 5vw; transform: translateZ(70px) rotate(1.4deg); }
.panel-two { margin-left: 28vw; margin-top: 20vh; transform: translateZ(30px) rotate(-2.1deg); }
.panel-three { margin-left: 8vw; margin-top: 8vh; transform: translateZ(90px) rotate(2.2deg); }
.bed-thought { margin: 34vh auto 0; max-width: 840px; transform: translateZ(35px) rotate(-1.1deg); }

.margin-note {
  position: relative;
  z-index: 7;
  max-width: 260px;
  margin: 34vh 0 0 58vw;
  transform: rotate(4deg);
}

.crack {
  position: absolute;
  z-index: 5;
  height: 1px;
  width: 62vw;
  background: var(--repair);
  opacity: 0.72;
  box-shadow: 0 0 16px rgba(200, 149, 106, 0.32);
  transform-origin: center;
  will-change: transform;
}

.crack-a { left: 28vw; top: 68vh; transform: rotate(var(--crack-angle-a)); }
.crack-b { left: 8vw; top: 18vh; width: 44vw; transform: rotate(var(--crack-angle-b)); }
.crack-c { right: -5vw; bottom: 20vh; width: 78vw; transform: rotate(var(--crack-angle-c)); }
.crack-d { left: 4vw; top: 58vh; width: 74vw; transform: rotate(var(--crack-angle-a)); }
.crack-e { left: 18vw; top: 42vh; width: 50vw; transform: rotate(var(--crack-angle-b)); }

.fracture-layer { min-height: 150vh; background: linear-gradient(180deg, rgba(10,26,47,0), rgba(10,26,47,.48)); }
.depth-layer { min-height: 150vh; overflow: hidden; }
.bed-layer { min-height: 100vh; background: radial-gradient(ellipse at 50% 55%, rgba(15,40,71,.34), transparent 42%); }

@keyframes repaired-pulse {
  0% { opacity: 0.55; transform: scaleX(0.98); }
  40% { opacity: 1; transform: scaleX(1.015); }
  65% { opacity: 0.82; transform: scaleX(0.995); }
  85% { opacity: 0.94; transform: scaleX(1.006); }
  100% { opacity: 0.72; transform: scaleX(1); }
}

.repaired .repair-seam {
  animation: repaired-pulse 2.4s cubic-bezier(0.25, 0.1, 0.25, 1) both;
}

@media (max-width: 760px) {
  .depth-progress { left: 12px; }
  .layer { padding-left: 54px; padding-right: 24px; }
  .shard-panel,
  .bed-thought { grid-template-columns: 1fr; max-width: 100%; }
  .panel-one,
  .panel-two,
  .panel-three,
  .bed-thought { margin-left: 0; }
  .rock-document,
  .hull-document { width: 72vw; }
  .margin-note { margin-left: 8vw; }
}