:root {
  --sheet: #f3ead6;
  --sheet-2: #e8dcc4;
  --ink: #241e16;
  --mute: #6a5e4e;
  --leaf: #3d5c3a;
  --leaf-bright: #5a7a52;
  --prussian: #1c3b62;
  --cyan: #2d5f8a;
  --seal: #8b3a32;
  --pest: #7a4e28;
  --ok: #3d5c3a;
  --line: rgba(36, 30, 22, 0.14);
  --shadow: 0 22px 48px rgba(36, 30, 22, 0.18);
  --serif: "Noto Serif SC", "Songti SC", "STSong", serif;
  --sans: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

section[id] {
  scroll-margin-top: 76px;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--sheet);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.75;
}

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

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

.app-link {
  color: var(--cyan);
  text-decoration: underline;
  text-underline-offset: 3px;
}

footer .app-link {
  color: #c9d8ea;
}

button {
  font-family: inherit;
  cursor: pointer;
}

code {
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 0.92em;
  background: rgba(28, 59, 98, 0.08);
  padding: 0.05em 0.35em;
}

.grain {
  pointer-events: none;
  position: fixed;
  inset: 0;
  z-index: 40;
  opacity: 0.18;
  background-image: url("images/texture.jpg");
  background-size: 640px auto;
  mix-blend-mode: multiply;
}

.skip {
  position: absolute;
  left: -999px;
}

.skip:focus {
  left: 12px;
  top: 12px;
  z-index: 60;
  background: var(--sheet);
  padding: 8px 12px;
}

.nav {
  position: sticky;
  top: 0;
  z-index: 30;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
  padding: 12px 28px;
  background: rgba(243, 234, 214, 0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--serif);
  font-weight: 700;
  letter-spacing: 0.04em;
}

.brand small {
  display: block;
  font-family: var(--sans);
  font-weight: 400;
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--mute);
}

.seal {
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  border: 2px solid var(--prussian);
  color: var(--prussian);
  border-radius: 2px;
}

.nav-toggle {
  display: none;
}

.nav-links {
  display: flex;
  flex-wrap: wrap;
  flex: 1 1 auto;
  min-width: 0;
  gap: 10px 18px;
  font-size: 14px;
  justify-content: flex-end;
}

.nav-links a {
  color: var(--mute);
  border-bottom: 1px solid transparent;
  padding-bottom: 2px;
}

.nav-links a.is-active,
.nav-links a:hover {
  color: var(--prussian);
  border-bottom-color: var(--cyan);
}

.hero {
  position: relative;
  min-height: min(92vh, 820px);
  display: grid;
  align-items: end;
  color: var(--sheet);
  overflow: hidden;
}

.hero img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.hero::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(28, 59, 98, 0.12) 0%, rgba(28, 59, 98, 0.45) 52%, rgba(18, 28, 40, 0.92) 100%);
}

.hero-inner {
  position: relative;
  z-index: 1;
  padding: 8vh 8vw 10vh;
  max-width: 920px;
}

.kicker,
.vlabel {
  font-style: italic;
  letter-spacing: 0.18em;
  font-size: 13px;
  color: #c9d8ea;
  margin: 0 0 12px;
}

.vlabel {
  color: var(--prussian);
}

h1,
h2,
h3 {
  font-family: var(--serif);
  font-weight: 700;
  line-height: 1.12;
  margin: 0 0 16px;
}

h1 {
  font-size: clamp(40px, 7.8vw, 88px);
  letter-spacing: -0.03em;
}

h2 {
  font-size: clamp(28px, 4vw, 42px);
}

h3 {
  font-size: 22px;
}

.lead {
  font-size: 18px;
  max-width: 46em;
  color: rgba(243, 234, 214, 0.9);
}

.meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 22px 0;
}

.chip {
  border: 1px solid rgba(243, 234, 214, 0.35);
  padding: 4px 10px;
  font-size: 12px;
  letter-spacing: 0.08em;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 18px;
  border: 1px solid currentColor;
  font-size: 14px;
  border-radius: 2px;
}

.btn-fill {
  background: var(--sheet);
  color: var(--prussian);
  border-color: var(--sheet);
}

.btn-ghost {
  background: transparent;
  color: inherit;
}

.disclaimer {
  margin: 18px 0 0;
  font-size: 13px;
  color: rgba(243, 234, 214, 0.72);
}

.wrap {
  width: min(1120px, calc(100% - 48px));
  margin: 0 auto;
  padding: 88px 0;
}

.section-head {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 24px;
  margin-bottom: 40px;
  align-items: start;
}

.section-head p:last-child {
  color: var(--mute);
  margin: 0;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.card {
  background: rgba(255, 250, 240, 0.62);
  border: 1px solid var(--line);
  padding: 22px 22px 18px;
  min-height: 220px;
}

.stamp {
  display: inline-block;
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--prussian);
  border: 1px solid var(--cyan);
  padding: 2px 8px;
  margin-bottom: 10px;
  font-style: italic;
}

.card ul,
.io-grid ul,
.rule-list {
  margin: 0;
  padding-left: 1.1em;
}

.card li,
.io-grid li,
.rule-list li {
  margin: 0.35em 0;
}

.alt {
  background: linear-gradient(180deg, #dfe8ef 0%, var(--sheet) 100%);
}

.ink {
  background: var(--prussian);
  color: var(--sheet);
}

.ink .vlabel,
.ink .section-head p:last-child,
.ink figcaption,
.ink .bench p {
  color: #c9d8ea;
}

.ink .card,
.ink .bench {
  background: rgba(18, 28, 40, 0.35);
  border-color: rgba(243, 234, 214, 0.16);
  color: var(--sheet);
}

.step {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 36px;
  align-items: center;
  margin-bottom: 72px;
}

.step.reverse {
  direction: rtl;
}

.step.reverse > * {
  direction: ltr;
}

.num {
  font-family: var(--serif);
  font-style: italic;
  font-size: 28px;
  color: var(--cyan);
  display: block;
  margin-bottom: 8px;
}

figure {
  margin: 0;
}

figure img {
  width: 100%;
  height: 320px;
  object-fit: cover;
  border-radius: 2px;
  box-shadow: var(--shadow);
}

figcaption {
  margin-top: 10px;
  font-size: 13px;
  color: var(--mute);
  font-style: italic;
}

.gate-demo {
  margin-top: 22px;
  padding: 14px 16px;
  border: 1px dashed var(--prussian);
  background: rgba(28, 59, 98, 0.06);
}

.clock-label {
  margin: 0 0 8px;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--mute);
}

.clock-track {
  height: 14px;
  background: rgba(36, 30, 22, 0.08);
  overflow: hidden;
}

.clock-track i {
  display: block;
  height: 100%;
  width: 98%;
  background: linear-gradient(90deg, var(--leaf), var(--cyan));
}

.clock-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  margin-top: 10px;
  font-size: 13px;
}

.clock-meta .btn {
  color: var(--prussian);
  border-color: var(--prussian);
  padding: 6px 12px;
}

.gate-status.ok {
  color: var(--leaf);
}

.gate-status.hot {
  color: var(--seal);
}

.bench-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.bench {
  padding: 18px 18px 14px;
  background: #fffaf0;
  border: 1px solid var(--line);
}

.bench h3 {
  font-size: 18px;
  margin-bottom: 8px;
}

.bench p {
  margin: 0;
  color: var(--mute);
  font-size: 14px;
}

.rule-list {
  font-size: 17px;
  max-width: 46em;
}

.io-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
}

.lots {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin-top: 18px;
}

.lot {
  border: 1px solid var(--line);
  padding: 12px;
  background: #fffaf0;
  text-align: left;
  color: var(--ink);
}

.lot.is-on {
  border-color: var(--prussian);
  box-shadow: 0 0 0 1px var(--prussian);
}

.lot .id {
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 12px;
}

.lot .size {
  font-family: var(--serif);
  font-size: 18px;
  margin: 4px 0;
}

footer {
  border-top: 1px solid var(--line);
  background: #121c28;
  color: #c9d8ea;
}

.footer-inner {
  padding: 32px 0;
  display: flex;
  justify-content: space-between;
  gap: 16px;
  font-size: 13px;
}

@media (max-width: 860px) {
  .nav {
    padding: 12px 16px;
  }

  .nav-links {
    flex: 1 1 100%;
    justify-content: flex-start;
    gap: 6px 12px;
    font-size: 13px;
  }

  .section-head,
  .grid-3,
  .step,
  .step.reverse,
  .io-grid,
  .bench-grid,
  .lots,
  .footer-inner {
    grid-template-columns: 1fr;
    direction: ltr;
    display: grid;
  }

  .footer-inner {
    display: flex;
    flex-direction: column;
  }

  h1 {
    font-size: 40px;
  }

  figure img {
    height: 220px;
  }

  .wrap {
    width: min(1120px, calc(100% - 32px));
    padding: 56px 0;
  }
}