:root {
  --paper: #f6f1e6;
  --paper-2: #fffdf8;
  --ink: #1c2430;
  --blue: #1e4b8c;
  --blue-2: #3a6cb0;
  --seal: #b4232c;
  --mute: #5c6573;
  --serif: "Noto Serif SC", "Songti SC", serif;
  --sans: "Noto Sans SC", "PingFang SC", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, Menlo, monospace;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
section[id] { scroll-margin-top: 76px; }

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.7;
}

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
.app-link { color: var(--blue); text-decoration: underline; text-underline-offset: 3px; }
button { font-family: inherit; cursor: pointer; }
code { font-family: var(--mono); background: rgba(30, 75, 140, 0.1); padding: 0.05em 0.35em; }

.xuan {
  pointer-events: none;
  position: fixed;
  inset: 0;
  z-index: 6;
  opacity: 0.22;
  background-image: url("images/texture.webp");
  background-size: 420px auto;
  mix-blend-mode: multiply;
}

.skip { position: absolute; left: -999px; }
.skip:focus { left: 10px; top: 10px; z-index: 80; background: var(--seal); color: #fff; padding: 8px; }

.seal-bar {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 12px 22px;
  background: rgba(246, 241, 230, 0.92);
  border-bottom: 1px solid rgba(28, 36, 48, 0.12);
}
.brand { font-family: var(--serif); font-size: 24px; }
.brand small {
  display: block;
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  color: var(--blue);
}
.nav-toggle {
  display: none;
  background: var(--blue);
  color: #fff;
  border: 0;
  padding: 8px 12px;
}
.slip-nav { display: flex; gap: 14px; align-items: center; font-size: 13px; }
.slip-nav a { color: var(--mute); }
.slip-nav a.is-active, .slip-nav a:hover { color: var(--blue); }
.slip-nav a.live { background: var(--blue); color: #fff; padding: 7px 12px; }

.wall-hero {
  display: grid;
  grid-template-columns: 0.95fr 1.05fr;
  gap: 28px;
  align-items: center;
  padding: 48px 6vw 64px;
  position: relative;
  z-index: 1;
}
.kicker {
  font-family: var(--mono);
  letter-spacing: 0.16em;
  font-size: 11px;
  color: var(--blue);
  margin: 0 0 12px;
}
h1, h2, h3 { font-family: var(--serif); margin: 0 0 14px; line-height: 1.15; }
h1 { font-size: clamp(34px, 5.2vw, 60px); }
h2 { font-size: clamp(26px, 3vw, 38px); }
h3 { font-size: 22px; }
.lead { max-width: 42em; }
.quiet { color: var(--mute); max-width: 46em; }

.cell-wall {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 6px;
  background: #d9c9a8;
  padding: 10px;
  box-shadow: 0 16px 40px rgba(28, 36, 48, 0.12);
}
.cell {
  aspect-ratio: 1;
  border: 0;
  background: #efe6d4;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--mute);
}
.cell.open { background: #fff; color: var(--blue); }
.cell.now { background: var(--seal); color: #fff; }

.reveal-demo { margin: 18px 0; }
.stamp-btn {
  background: var(--seal);
  color: #fff;
  border: 0;
  padding: 10px 16px;
  font-family: var(--serif);
  font-size: 16px;
}
#reveal-msg { margin: 8px 0 0; font-size: 14px; }

.cta { display: flex; flex-wrap: wrap; gap: 10px; }
.btn { display: inline-flex; align-items: center; padding: 10px 16px; border: 1px solid currentColor; }
.btn.fill { background: var(--blue); color: #fff; border-color: var(--blue); }
.btn.ghost { background: transparent; }

.sheet { width: min(1080px, calc(100% - 40px)); margin: 0 auto; padding: 72px 0; }
.blue-band { background: #e7eef6; }
.blue-band .app-link { color: var(--blue); }

.tri { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; margin-top: 28px; }
.tri article, .grid6 article, .grid3 article, .io > div {
  background: var(--paper-2);
  border: 1px solid rgba(30, 75, 140, 0.16);
  padding: 16px 18px;
}
.seal-card { box-shadow: inset 0 0 0 2px var(--seal); }
.tri ul, .io ul, .bound { margin: 0; padding-left: 1.1em; }
.tri li, .io li, .bound li { margin: 0 0 6px; }

.step {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  align-items: center;
  margin: 32px 0;
}
.step.rev { direction: rtl; }
.step.rev > * { direction: ltr; }
.num { font-family: var(--mono); color: var(--blue); letter-spacing: 0.12em; font-size: 12px; }
.step figure { margin: 0; }
.step img { border: 1px solid rgba(30, 75, 140, 0.2); }
.step figcaption { margin-top: 8px; font-size: 13px; color: var(--mute); }

.grid6, .grid3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin-top: 28px; }
.io { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin-top: 24px; }
.bound { max-width: 46em; }

footer {
  padding: 20px 24px 36px;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--mute);
}

@media (max-width: 900px) {
  .wall-hero, .tri, .step, .step.rev, .grid6, .grid3, .io { grid-template-columns: 1fr; }
  .step.rev { direction: ltr; }
  .cell-wall { grid-template-columns: repeat(4, 1fr); }
  .nav-toggle { display: inline-block; }
  .slip-nav {
    display: none;
    position: absolute;
    right: 12px;
    top: 56px;
    flex-direction: column;
    background: var(--paper);
    border: 1px solid rgba(30, 75, 140, 0.2);
    padding: 10px;
    min-width: 180px;
  }
  .slip-nav.open { display: flex; }
}