:root {
  --paper: #efe8dc;
  --ink: #141414;
  --nav-h: calc(48 * var(--u));
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; }
body {
  font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  color: var(--ink);
  background: #111;
  overflow: hidden;
}

.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-h);
  z-index: 50;
  display: flex;
  align-items: center;
  gap: calc(18 * var(--u));
  padding: 0 calc(20 * var(--u));
  background: rgba(10, 10, 10, 0.88);
  color: #f3f3f3;
  font-size: calc(12 * var(--u));
  letter-spacing: 0.12em;
}
.nav a { color: inherit; text-decoration: none; opacity: 0.55; }
.nav a:hover, .nav a.is-on { opacity: 1; }
.nav .brand { margin-right: auto; opacity: 0.9; letter-spacing: 0.2em; }

.stage {
  position: relative;
  height: calc(1080 * var(--u));
  padding-top: var(--nav-h);
  overflow: hidden;
}

.paper-grain::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: 0.22;
  mix-blend-mode: multiply;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='180' height='180'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.55'/%3E%3C/svg%3E");
}

/* 皱纸底 + 黑白漫画揭开 */
.preloader {
  position: absolute;
  inset: 0;
  z-index: 40;
  pointer-events: none;
  overflow: hidden;
  background: transparent;
}
.preloader__paper,
.preloader__panel {
  background-color: #f4f1ea;
  background-image: url("./vendor/paper-texture.webp");
  background-size: cover;
  background-position: center;
}
.preloader__paper {
  position: absolute;
  inset: 0;
}
.preloader__panel {
  position: absolute;
  box-sizing: border-box;
  border: max(1px, calc(7 * var(--u))) solid #111;
  box-shadow: calc(5 * var(--u)) calc(5 * var(--u)) 0 #000;
  opacity: 0;
  will-change: transform;
  z-index: 3;
}
.preloader__speed,
.preloader__tone {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  opacity: 0;
  z-index: 8;
}
.preloader__speed { transform-origin: 50% 50%; }
.preloader__hud {
  position: absolute;
  inset: 0;
  z-index: 12;
  display: grid;
  place-items: center;
}
.preloader__num {
  font-family: "Arial Black", Impact, "PingFang SC", sans-serif;
  font-size: clamp(calc(42 * var(--u)), calc(153.6 * var(--u)), calc(88 * var(--u)));
  font-weight: 900;
  letter-spacing: -0.04em;
  color: #111;
  mix-blend-mode: multiply;
  -webkit-text-stroke: calc(6 * var(--u)) #f4f1ea;
  paint-order: stroke fill;
}
.preloader__replay {
  position: absolute;
  right: calc(18 * var(--u));
  bottom: calc(16 * var(--u));
  z-index: 30;
  pointer-events: auto;
  border: max(1px, calc(3 * var(--u))) solid #111;
  background: #f4f1ea;
  color: #111;
  font-size: calc(11 * var(--u));
  letter-spacing: 0.12em;
  padding: calc(7 * var(--u)) calc(12 * var(--u));
  cursor: pointer;
  opacity: 0;
  box-shadow: calc(3 * var(--u)) calc(3 * var(--u)) 0 #000;
}
.preloader.is-done > :not(.preloader__replay) { visibility: hidden; }
.preloader.is-done .preloader__replay {
  opacity: 1;
  pointer-events: auto;
}

.preloader__cut {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 9;
  overflow: visible;
}
.preloader__tone-ring {
  position: absolute;
  left: 50%;
  top: 50%;
  width: min(calc(806.4 * var(--u)), calc(280 * var(--u)));
  height: min(calc(806.4 * var(--u)), calc(280 * var(--u)));
  border-radius: 50%;
  transform: translate(-50%, -50%) scale(0.2);
  opacity: 0;
  z-index: 7;
  background:
    repeating-radial-gradient(circle, #111 0 1.5px, transparent 1.5px calc(7 * var(--u)));
  mix-blend-mode: multiply;
  pointer-events: none;
}
.preloader__page {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 49%;
  background-color: #f4f1ea;
  background-image: url("./vendor/paper-texture.webp");
  background-size: cover;
  background-position: center;
  border: max(1px, calc(8 * var(--u))) solid #111;
  box-shadow: calc(6 * var(--u)) calc(6 * var(--u)) 0 #000;
  z-index: 3;
  will-change: transform;
  overflow: hidden;
}
.preloader__page--left { left: 0; }
.preloader__page--right { right: 0; }
.preloader__page i {
  position: absolute;
  border: max(1px, calc(3 * var(--u))) solid #111;
  display: block;
}
.preloader__page i:first-child {
  top: 8%;
  left: 8%;
  right: 8%;
  height: 38%;
}
.preloader__page i:last-child {
  top: 52%;
  left: 8%;
  right: 8%;
  bottom: 8%;
}
.preloader__gutter {
  position: absolute;
  left: 49%;
  width: 2%;
  top: 0;
  bottom: 0;
  background: #111;
  z-index: 4;
  transform-origin: 50% 50%;
}
.preloader__rip {
  position: absolute;
  inset: 0;
  z-index: 3;
  overflow: hidden;
  background-color: #f4f1ea;
  background-image: url("./vendor/paper-texture.webp");
  background-size: cover;
  will-change: transform;
}
.preloader__rip b {
  position: absolute;
  border: max(1px, calc(6 * var(--u))) solid #111;
  box-shadow: calc(4 * var(--u)) calc(4 * var(--u)) 0 #000;
  background:
    repeating-radial-gradient(circle, #111 0 1px, transparent 1px calc(6 * var(--u)));
  opacity: 0.35;
}
.preloader__rip--a b:nth-child(1) { top: 6%; left: 6%; width: 42%; height: 38%; }
.preloader__rip--a b:nth-child(2) { top: 50%; left: 8%; width: 36%; height: 42%; }
.preloader__rip--a b:nth-child(3) { top: 10%; left: 52%; width: 22%; height: 28%; }
.preloader__rip--a b:nth-child(4) { display: none; }
.preloader__rip--b b:nth-child(1) { top: 8%; right: 7%; width: 40%; height: 44%; }
.preloader__rip--b b:nth-child(2) { top: 56%; right: 8%; width: 38%; height: 34%; }
.preloader__rip--b b:nth-child(3) { top: 14%; right: 48%; width: 18%; height: 24%; }
.preloader__rip--b b:nth-child(4) { display: none; }

.preloader__peel {
  position: absolute;
  inset: 0;
  z-index: 3;
  transform-origin: 0 0;
  background-color: #080808;
  background-size: contain;
  background-repeat: no-repeat;
  background-position: center center;
  box-shadow: calc(18 * var(--u)) calc(18 * var(--u)) calc(40 * var(--u)) rgba(0, 0, 0, 0.4);
  will-change: transform;
}

.placeholder {
  opacity: 0.45;
  border-bottom: 1px dashed currentColor;
}
.note {
  position: absolute;
  left: calc(20 * var(--u));
  bottom: calc(16 * var(--u));
  font-size: calc(11 * var(--u));
  letter-spacing: 0.08em;
  opacity: 0.5;
}

@media (prefers-reduced-motion: reduce) {
  html:not(.motion-on) .preloader { display: none; }
}