:root {
  color-scheme: dark;
  --bg: #090f16;
  --surface: #111a26;
  --surface-strong: #172333;
  --line: #263446;
  --text: #f5f8fc;
  --muted: #9eb0c6;
  --accent: #64e0bd;
  --accent-dark: #062c25;
  --link: #8de8cf;
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    "Microsoft YaHei", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  background: var(--bg);
  color: var(--text);
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at 85% 0%, rgba(100, 224, 189, 0.12), transparent 30rem),
    var(--bg);
  line-height: 1.75;
}

a {
  color: var(--link);
  text-underline-offset: 0.2em;
}

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

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 84px;
  gap: 24px;
  border-bottom: 1px solid var(--line);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: var(--text);
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 44px;
  height: 44px;
  place-items: center;
  border-radius: 14px;
  background: var(--accent);
  color: var(--accent-dark);
  font-weight: 900;
  letter-spacing: -0.08em;
}

.brand strong,
.brand small {
  display: block;
}

.brand small {
  margin-top: -2px;
  color: var(--muted);
  font-size: 0.74rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

nav {
  display: flex;
  gap: 22px;
}

nav a {
  color: var(--muted);
  font-weight: 700;
  text-decoration: none;
}

nav a:hover,
nav a[aria-current="page"] {
  color: var(--accent);
}

main {
  padding-block: 72px;
}

.hero {
  max-width: 840px;
  padding-block: 48px 72px;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.14em;
}

h1 {
  margin: 0;
  font-size: clamp(2.3rem, 6vw, 4.6rem);
  line-height: 1.08;
  letter-spacing: -0.04em;
}

.hero-copy {
  max-width: 740px;
  margin: 28px 0 0;
  color: var(--muted);
  font-size: clamp(1rem, 2vw, 1.2rem);
}

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

.button {
  display: inline-flex;
  min-height: 46px;
  align-items: center;
  justify-content: center;
  padding: 10px 18px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text);
  font-weight: 800;
  text-decoration: none;
}

.button-primary {
  border-color: var(--accent);
  background: var(--accent);
  color: var(--accent-dark);
}

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

.card,
.notice,
.document section {
  border: 1px solid var(--line);
  border-radius: 18px;
  background: rgba(17, 26, 38, 0.9);
}

.card {
  padding: 26px;
}

.card h2,
.notice h2 {
  margin-top: 0;
}

.card p,
.notice p {
  color: var(--muted);
}

.notice {
  margin-top: 18px;
  padding: 26px;
}

.document {
  width: min(920px, calc(100% - 40px));
}

.document-heading {
  margin-bottom: 34px;
}

.document-heading h1 {
  font-size: clamp(2rem, 5vw, 3.5rem);
}

.document-heading > p:not(.eyebrow) {
  margin: 8px 0 0;
  color: var(--muted);
}

.document section {
  margin-top: 18px;
  padding: clamp(22px, 5vw, 38px);
}

.document h2 {
  margin: 0 0 14px;
  font-size: 1.3rem;
}

.document p,
.document li,
.document dd {
  color: #c7d2e0;
}

.document li + li {
  margin-top: 8px;
}

.document dt {
  margin-top: 16px;
  color: var(--accent);
  font-weight: 800;
}

.document dd {
  margin-left: 0;
}

code {
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 2px 6px;
  background: var(--surface-strong);
  color: var(--accent);
}

details {
  border-top: 1px solid var(--line);
  padding: 16px 0;
}

details:first-of-type {
  border-top: 0;
}

summary {
  cursor: pointer;
  font-weight: 800;
}

footer {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  padding-block: 30px 48px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.9rem;
}

footer a {
  color: var(--muted);
}

@media (max-width: 760px) {
  .site-header {
    align-items: flex-start;
    flex-direction: column;
    padding-block: 18px;
  }

  .grid {
    grid-template-columns: 1fr;
  }

  main {
    padding-block: 42px;
  }

  .hero {
    padding-block: 24px 54px;
  }
}