:root {
  --indigo: #0b1e38;
  --indigo-deep: #071426;
  --indigo-mid: #16365c;
  --wave: #7eb3d9;
  --paper: #f4ead4;
  --paper-2: #e9dcc0;
  --paper-3: #dcc9a4;
  --ink: #1a1612;
  --mute: #6a5c48;
  --vermillion: #c23a22;
  --gold: #c4a056;
  --seal: #b13220;
  --ok: #2f6b4f;
  --line: rgba(26, 22, 18, 0.12);
  --shadow: 0 18px 50px rgba(7, 20, 38, 0.22);
  --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: 72px;
}

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;
}

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

.grain {
  pointer-events: none;
  position: fixed;
  inset: 0;
  z-index: 5;
  opacity: 0.07;
  background-image: url("images/texture.webp");
  background-size: 900px auto;
  mix-blend-mode: multiply;
}

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

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

.nav {
  position: sticky;
  top: 0;
  z-index: 30;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 28px;
  background: rgba(244, 234, 212, 0.88);
  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;
}

.seal {
  width: 36px;
  height: 36px;
  border: 2px solid var(--seal);
  color: var(--seal);
  border-radius: 4px;
  display: grid;
  place-items: center;
  font-family: var(--serif);
  font-size: 18px;
  transform: rotate(-8deg);
  box-shadow: inset 0 0 0 1px var(--seal);
}

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

.nav-links {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.nav-links a {
  font-size: 13px;
  padding: 6px 10px;
  border-radius: 999px;
  color: var(--mute);
}

.nav-links a:hover,
.nav-links a.is-active {
  color: var(--indigo);
  background: rgba(11, 30, 56, 0.06);
}

.nav-links a.live {
  color: #fff;
  background: var(--vermillion, #c23a22);
}

.nav-toggle {
  display: none;
  border: 1px solid var(--line);
  background: transparent;
  padding: 8px 12px;
  border-radius: 8px;
}

.hero {
  position: relative;
  min-height: 92vh;
  color: var(--paper);
  overflow: hidden;
  background: var(--indigo-deep);
}

.hero img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: 55% 40%;
}

.hero::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    linear-gradient(90deg, rgba(7, 20, 38, 0.86) 0%, rgba(7, 20, 38, 0.42) 52%, rgba(7, 20, 38, 0.2) 100%),
    linear-gradient(180deg, rgba(7, 20, 38, 0.15) 0%, rgba(7, 20, 38, 0.55) 100%);
}

.hero-inner {
  position: relative;
  z-index: 1;
  max-width: 1180px;
  margin: 0 auto;
  padding: 88px 28px 64px;
  display: grid;
  grid-template-columns: 48px 1fr;
  gap: 28px;
  min-height: 92vh;
  align-items: stretch;
}

.hero-inner > div:last-child {
  align-self: end;
}

.vlabel {
  writing-mode: vertical-rl;
  letter-spacing: 0.45em;
  font-family: var(--serif);
  font-size: 13px;
  color: var(--gold);
  border-right: 1px solid rgba(196, 160, 86, 0.4);
  padding-right: 14px;
  height: min-content;
}

.kicker {
  font-size: 12px;
  letter-spacing: 0.28em;
  color: var(--gold);
  margin: 0 0 16px;
}

.hero h1 {
  font-family: var(--serif);
  font-size: clamp(40px, 7vw, 84px);
  line-height: 1.08;
  margin: 0 0 18px;
  font-weight: 700;
}

.hero .lead {
  max-width: 36em;
  font-size: 18px;
  color: rgba(244, 234, 212, 0.88);
  margin: 0 0 28px;
}

.meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 28px;
}

.chip {
  border: 1px solid rgba(244, 234, 212, 0.35);
  padding: 4px 12px;
  border-radius: 999px;
  font-size: 12px;
  letter-spacing: 0.08em;
}

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

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  border-radius: 999px;
  font-size: 14px;
  border: 1px solid transparent;
}

.btn-fill {
  background: var(--paper);
  color: var(--indigo);
}

.btn-ghost {
  border-color: rgba(244, 234, 212, 0.45);
  color: var(--paper);
  background: transparent;
}

.disclaimer {
  margin: 22px 0 0;
  font-size: 12px;
  color: rgba(244, 234, 212, 0.62);
}

.wrap {
  max-width: 1180px;
  margin: 0 auto;
  padding: 72px 28px;
}

.section-head {
  display: grid;
  grid-template-columns: 48px 1fr;
  gap: 24px;
  margin-bottom: 36px;
}

.section-head h2 {
  font-family: var(--serif);
  font-size: clamp(28px, 4vw, 40px);
  margin: 0 0 8px;
  line-height: 1.2;
}

.section-head p {
  margin: 0;
  color: var(--mute);
  max-width: 44em;
}

.vlabel.ink {
  color: var(--indigo-mid);
  border-right-color: rgba(22, 54, 92, 0.25);
}

.grid-3,
.grid-2,
.grid-4 {
  display: grid;
  gap: 18px;
}

.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

.card {
  background: rgba(255, 251, 242, 0.72);
  border: 1px solid var(--line);
  border-radius: 4px 18px 4px 18px;
  padding: 22px;
  box-shadow: 0 1px 0 rgba(255, 255, 255, 0.6) inset;
  position: relative;
}

.card::before {
  content: "";
  position: absolute;
  top: 10px;
  right: 14px;
  width: 10px;
  height: 10px;
  border: 1px solid var(--gold);
  transform: rotate(45deg);
}

.card h3 {
  font-family: var(--serif);
  margin: 0 0 8px;
  font-size: 20px;
}

.card p,
.card li {
  color: var(--mute);
  font-size: 14px;
}

.card ul {
  margin: 8px 0 0;
  padding-left: 1.1em;
}

.stamp {
  display: inline-block;
  font-family: var(--serif);
  font-size: 11px;
  color: var(--seal);
  border: 1.5px solid var(--seal);
  padding: 1px 7px;
  transform: rotate(-6deg);
  margin-bottom: 10px;
}

.band {
  background: var(--indigo);
  color: var(--paper);
}

.band .vlabel {
  color: var(--gold);
  border-right-color: rgba(196, 160, 86, 0.35);
}

.band .section-head p {
  color: rgba(244, 234, 212, 0.72);
}

.steps {
  display: grid;
  gap: 0;
}

.step {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  min-height: 320px;
  border-top: 1px solid rgba(244, 234, 212, 0.12);
}

.step:nth-child(even) {
  grid-template-columns: 0.95fr 1.05fr;
}

.step:nth-child(even) .step-copy {
  order: 1;
}

.step:nth-child(even) figure {
  order: 2;
}

.step figure {
  margin: 0;
  overflow: hidden;
  background: var(--indigo-deep);
}

.step img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  min-height: 320px;
}

.step-copy {
  padding: 40px 36px;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.idx {
  font-family: var(--serif);
  color: var(--gold);
  font-size: 13px;
  letter-spacing: 0.2em;
  margin-bottom: 8px;
}

.step-copy h3 {
  font-family: var(--serif);
  font-size: 28px;
  margin: 0 0 12px;
}

.step-copy p {
  margin: 0 0 12px;
  color: rgba(244, 234, 212, 0.82);
}

.step-copy ul {
  margin: 0;
  padding-left: 1.15em;
  color: rgba(244, 234, 212, 0.7);
  font-size: 14px;
}

.workbench {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
}

.col {
  background: #fffaf0;
  border: 1px solid var(--line);
  min-height: 280px;
  padding: 16px;
}

.col header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 12px;
  font-family: var(--serif);
}

.col header span {
  font-size: 11px;
  color: var(--mute);
  font-family: var(--sans);
}

.wave {
  display: flex;
  align-items: flex-end;
  gap: 2px;
  height: 36px;
  margin-bottom: 12px;
}

.wave i {
  width: 3px;
  background: var(--indigo-mid);
  display: block;
  border-radius: 1px;
}

.bubble {
  font-size: 12px;
  padding: 8px 10px;
  border-radius: 8px;
  margin-bottom: 8px;
  background: #f0e6cf;
}

.bubble em {
  font-style: normal;
  background: #f3d27a;
  padding: 0 2px;
}

.bubble.me {
  background: #dce8f4;
}

.block-row {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  padding: 7px 0;
  border-bottom: 1px dashed var(--line);
}

.status {
  font-size: 10px;
  padding: 1px 6px;
  border-radius: 999px;
}

.status.done { background: #e4f0e8; color: var(--ok); }
.status.run { background: #e4edf8; color: var(--indigo-mid); }
.status.wait { background: #eee8dc; color: var(--mute); }

.mock {
  background: #0b1d4c;
  color: #fff;
  border-radius: 6px;
  padding: 10px;
  font-size: 11px;
  min-height: 88px;
}

.mock small {
  display: block;
  opacity: 0.7;
  margin-top: 4px;
}

.swatches {
  display: flex;
  gap: 6px;
  margin: 8px 0 12px;
}

.swatches b {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  display: block;
}

.rule-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
  background: #fffaf0;
}

.rule-table th,
.rule-table td {
  text-align: left;
  padding: 12px 14px;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}

.rule-table th {
  font-family: var(--serif);
  background: var(--indigo);
  color: var(--paper);
  font-weight: 600;
}

.rule-table td:first-child,
.rule-table th:first-child {
  white-space: nowrap;
}

.rule-table tr:nth-child(even) td {
  background: rgba(11, 30, 56, 0.03);
}

.example {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 24px;
  align-items: start;
}

.quote {
  background: var(--indigo);
  color: var(--paper);
  padding: 28px;
  border-radius: 4px 28px 4px 4px;
}

.quote h3 {
  font-family: var(--serif);
  margin: 0 0 16px;
}

.quote dl {
  display: grid;
  grid-template-columns: 88px 1fr;
  gap: 6px 10px;
  margin: 0;
  font-size: 14px;
}

.quote dt {
  color: var(--gold);
}

.quote dd {
  margin: 0;
}

.fold-note {
  font-size: 13px;
  color: var(--mute);
  margin-top: 16px;
}

.io {
  display: grid;
  grid-template-columns: 1fr 48px 1fr;
  gap: 12px;
  align-items: stretch;
}

.arrow {
  display: grid;
  place-items: center;
  font-family: var(--serif);
  color: var(--gold);
  font-size: 28px;
}

.footer {
  background: var(--indigo-deep);
  color: rgba(244, 234, 212, 0.72);
  padding: 40px 28px 28px;
}

.footer-inner {
  max-width: 1180px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
  font-size: 13px;
}

.footer strong {
  color: var(--paper);
  font-family: var(--serif);
  font-size: 18px;
  display: block;
  margin-bottom: 6px;
}

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

.footer .app-link {
  color: var(--paper);
}

.reveal {
  opacity: 0;
  transform: translateY(16px);
  animation: rise 0.7s ease forwards;
}

@keyframes rise {
  to {
    opacity: 1;
    transform: none;
  }
}

@media (max-width: 980px) {
  .grid-3,
  .grid-4,
  .workbench,
  .example,
  .io,
  .step,
  .step:nth-child(even) {
    grid-template-columns: 1fr;
  }

  .step:nth-child(even) .step-copy,
  .step:nth-child(even) figure {
    order: 0;
  }

  .hero-inner,
  .section-head {
    grid-template-columns: 1fr;
  }

  .vlabel {
    writing-mode: horizontal-tb;
    border-right: 0;
    border-bottom: 1px solid currentColor;
    padding: 0 0 8px;
    letter-spacing: 0.28em;
  }

  .nav-toggle {
    display: block;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 60px;
    right: 12px;
    left: 12px;
    background: var(--paper);
    border: 1px solid var(--line);
    padding: 8px;
    flex-direction: column;
  }

  .nav-links.open {
    display: flex;
    box-shadow: var(--shadow);
    z-index: 40;
  }

  .col {
    min-height: 0;
  }

  .rule-table {
    display: block;
    overflow-x: auto;
  }

  .hero {
    min-height: 100svh;
  }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { animation: none; opacity: 1; transform: none; }
}