:root {
  --paper: #e6eae4;
  --paper-alt: #dce3db;
  --ink: #161f26;
  --muted: #4e5a61;
  --signal: #b24a22;
  --line: #2c5a48;
  --hair: #c4cbc2;
  --board: #141c21;
  --board-ink: #dce6df;
  --board-mute: #8aa094;
  --lamp: #c9a227;
  --ease-out: cubic-bezier(0.23, 1, 0.32, 1);
  --font-sans: -apple-system, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
    "Noto Sans SC", sans-serif;
  --font-display: "Syne", var(--font-sans);
  --font-mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
}

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

html {
  scroll-behavior: smooth;
}

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

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

a {
  color: inherit;
  text-decoration-thickness: 1px;
  text-underline-offset: 0.22em;
}

button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  cursor: pointer;
}

h1,
h2,
h3 {
  margin: 0;
  font-family: var(--font-sans);
  font-weight: 600;
  line-height: 1.22;
  letter-spacing: 0.01em;
  text-wrap: balance;
}

p {
  margin: 0;
}

ul,
ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  left: 12px;
  top: -48px;
  z-index: 20;
  padding: 8px 12px;
  background: var(--ink);
  color: var(--paper);
}

.skip-link:focus {
  top: 12px;
}

.shell {
  width: min(1120px, calc(100% - 40px));
  margin-inline: auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  border-top: 4px solid var(--line);
  border-bottom: 1px solid var(--hair);
  background: color-mix(in srgb, var(--paper) 92%, white);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 68px;
  gap: 24px;
  position: relative;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
}

.mark {
  width: 28px;
  height: 28px;
  flex: none;
  color: var(--ink);
}

.mark-lamp {
  color: var(--signal);
  fill: var(--signal);
}

.mark-on-dark {
  color: var(--board-ink);
}

.brand-text {
  display: flex;
  align-items: baseline;
  gap: 8px;
}

.brand-en {
  font-family: var(--font-display);
  font-size: 15px;
  font-weight: 800;
  letter-spacing: 0.12em;
}

.brand-zh {
  font-size: 15px;
  font-weight: 500;
}

.nav-toggle {
  display: none;
  padding: 6px 0;
  border-bottom: 1px solid var(--ink);
}

.nav-list {
  display: flex;
  gap: 28px;
}

.nav-list a {
  text-decoration: none;
  font-size: 15px;
}

.nav-list a:hover {
  color: var(--signal);
}

.hero,
.section,
.site-footer {
  scroll-margin-top: 76px;
}

.hero {
  padding: 72px 0 88px;
  border-bottom: 1px solid var(--hair);
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(320px, 0.85fr);
  gap: 64px;
  align-items: end;
}

.hero-kicker {
  margin-bottom: 18px;
  color: var(--line);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
}

.hero h1 {
  max-width: 9em;
  font-size: clamp(2.4rem, 5.2vw, 4rem);
  font-weight: 600;
}

.hero-lead {
  max-width: 36em;
  margin-top: 20px;
  color: var(--muted);
  font-size: 17px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 32px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 18px;
  text-decoration: none;
  transition:
    background-color 160ms var(--ease-out),
    color 160ms var(--ease-out),
    transform 100ms var(--ease-out);
}

.btn:active {
  transform: scale(0.97);
}

.btn-primary {
  background: var(--ink);
  color: var(--paper);
}

.btn-primary:hover {
  background: var(--signal);
}

.btn-ghost {
  border: 1px solid var(--ink);
}

.btn-ghost:hover {
  background: var(--ink);
  color: var(--paper);
}

.board {
  background: var(--board);
  color: var(--board-ink);
  padding: 22px 22px 10px;
}

.board-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 18px;
  padding-bottom: 16px;
  border-bottom: 1px solid #2a353b;
}

.board-code {
  margin-bottom: 6px;
  color: var(--lamp);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
}

.board h2 {
  font-size: 18px;
  font-weight: 500;
}

.board-clock {
  font-family: var(--font-mono);
  font-size: 13px;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.04em;
  color: var(--board-mute);
}

.board-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font-mono);
  font-size: 13px;
}

.board-table th {
  padding: 0 0 10px;
  color: var(--board-mute);
  font-weight: 400;
  text-align: left;
}

.board-table td {
  padding: 12px 8px 12px 0;
  border-top: 1px solid #2a353b;
  vertical-align: middle;
}

.board-table td:last-child,
.board-table th:last-child {
  text-align: right;
  padding-right: 0;
}

.board-table .is-current td {
  color: #f2efe4;
}

.led {
  display: inline-block;
  width: 7px;
  height: 7px;
  margin-right: 8px;
  border-radius: 50%;
  background: #44524c;
  vertical-align: 1px;
}

.led-on {
  background: var(--line);
}

.led-live {
  background: var(--lamp);
  animation: pulse 1.8s var(--ease-out) infinite;
}

.section {
  padding: 88px 0;
}

.section-alt {
  background: var(--paper-alt);
}

.section-head {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 40px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--hair);
}

.section-head h2,
.method-copy h2,
.about-block h2 {
  font-size: clamp(1.6rem, 3vw, 2rem);
}

.section-head p {
  color: var(--muted);
}

.track-layout {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 48px;
}

.track-feature h3,
.track-row h3 {
  font-size: 28px;
  margin-top: 8px;
}

.track-feature p,
.track-row p {
  margin-top: 14px;
  color: var(--muted);
}

.track-meta {
  color: var(--line);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
}

.track-points {
  margin-top: 24px;
  border-top: 1px solid var(--hair);
}

.track-points li {
  padding: 12px 0;
  border-bottom: 1px solid var(--hair);
}

.track-row {
  padding: 22px 0;
  border-bottom: 1px solid var(--hair);
}

.track-row:first-child {
  padding-top: 0;
}

.method-grid {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: 64px;
  align-items: start;
}

.method-copy p {
  max-width: 32em;
  margin-top: 16px;
  color: var(--muted);
}

.method-list li {
  padding: 22px 0 22px 20px;
  border-top: 1px solid var(--hair);
  border-left: 3px solid transparent;
}

.method-list li:first-child {
  border-left-color: var(--line);
}

.method-list h3 {
  font-size: 20px;
}

.method-list p {
  margin-top: 8px;
  color: var(--muted);
}

.about-block {
  max-width: 46em;
}

.about-block p {
  margin-top: 16px;
  font-size: 18px;
  color: var(--muted);
}

.site-footer {
  background: var(--board);
  color: var(--board-ink);
  padding: 40px 0 28px;
}

.footer-grid {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding-bottom: 28px;
  border-bottom: 1px solid #2a353b;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.footer-name {
  font-weight: 600;
}

.footer-note,
.footer-legal {
  color: var(--board-mute);
}

.footer-links {
  display: flex;
  gap: 24px;
}

.footer-links a {
  text-decoration: none;
}

.footer-links a:hover,
.beian-link:hover {
  color: #f2efe4;
}

.footer-legal {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding-top: 20px;
  font-size: 13px;
}

.beian-link {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.02em;
  color: var(--board-ink);
}

:focus-visible {
  outline: 2px solid var(--signal);
  outline-offset: 3px;
}

::selection {
  background: var(--line);
  color: #f3f6f1;
}

@keyframes pulse {
  0%,
  100% {
    opacity: 1;
  }
  50% {
    opacity: 0.35;
  }
}

@media (hover: hover) and (pointer: fine) {
  .nav-list a,
  .footer-links a,
  .beian-link {
    transition: color 160ms var(--ease-out);
  }
}

@media (max-width: 860px) {
  .shell {
    width: min(1120px, calc(100% - 32px));
  }

  .nav-toggle {
    display: inline-flex;
  }

  .nav-list {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    flex-direction: column;
    gap: 0;
    min-width: 0;
    background: var(--paper);
    border: 1px solid var(--hair);
    border-top: 0;
  }

  .nav.is-open .nav-list {
    display: flex;
  }

  .nav-list a {
    display: block;
    padding: 12px 16px;
  }

  .hero,
  .section {
    padding: 56px 0;
  }

  .hero-grid,
  .track-layout,
  .method-grid,
  .footer-grid,
  .footer-legal,
  .section-head {
    grid-template-columns: 1fr;
    display: flex;
    flex-direction: column;
    align-items: stretch;
  }

  .hero-grid,
  .track-layout,
  .method-grid {
    gap: 36px;
  }

  .hero h1 {
    max-width: none;
  }

  .track-feature h3,
  .track-row h3 {
    font-size: 24px;
  }

  .board {
    width: 100%;
  }

  .footer-legal {
    align-items: flex-start;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .led-live,
  .btn {
    animation: none;
    transition: none;
  }
}