*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
:root {
  --paper: #f2eee6;
  --paper-2: #e8e2d6;
  --paper-3: #ddd5c6;
  --ink: #0f0f0d;
  --ink-3: #2a2a26;
  --muted: #6d685f;
  --muted-dark: #8f8a80;
  --line: rgba(15, 15, 13, 0.12);
  --line-dark: rgba(242, 238, 230, 0.12);
  --accent: #ff5a1f;
  --display: "Clash Display", "Satoshi", system-ui, sans-serif;
  --body: "Satoshi", system-ui, -apple-system, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, monospace;
  --px: 20px;
  --ease: cubic-bezier(0.19, 1, 0.22, 1);
}
html {
  scroll-behavior: smooth;
}
body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--body);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
::selection {
  background: var(--accent);
  color: var(--ink);
}
.wrap {
  max-width: 1360px;
  margin: 0 auto;
  padding: 0 var(--px);
}
.label {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
  display: inline-flex;
  gap: 10px;
}
.label b {
  font-weight: 500;
  color: var(--accent);
}

/* nav */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(242, 238, 230, 0.86);
  backdrop-filter: blur(18px) saturate(1.4);
  -webkit-backdrop-filter: blur(18px) saturate(1.4);
  border-bottom: 1px solid var(--line);
}
.nav-in {
  height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.logo {
  font-family: var(--display);
  font-weight: 600;
  font-size: 24px;
  letter-spacing: -0.04em;
  text-decoration: none;
  color: var(--ink);
}
.logo i {
  font-style: normal;
  color: var(--accent);
}
.nav-right {
  display: flex;
  align-items: center;
  gap: 18px;
}
.back {
  font-size: 14px;
  font-weight: 500;
  color: var(--ink);
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}
.back span {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  border: 1px solid var(--line);
  display: grid;
  place-items: center;
  transition:
    background 0.3s,
    border-color 0.3s;
}
.back:hover span {
  background: var(--accent);
  border-color: var(--accent);
}
.langs {
  display: flex;
  font-family: var(--mono);
  font-size: 12px;
}
.langs button {
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px 7px;
  color: var(--muted);
  font: inherit;
}
.langs .on {
  color: var(--ink);
  font-weight: 500;
}

/* header */
.head {
  padding: 88px 0 56px;
  border-bottom: 1px solid var(--line);
}
.head h1 {
  font-family: var(--display);
  font-weight: 500;
  font-size: clamp(52px, 10vw, 168px);
  line-height: 0.9;
  letter-spacing: -0.045em;
  margin: 24px 0 28px;
}
.head h1 .accent {
  color: var(--accent);
}
.meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 28px;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--muted);
  text-transform: uppercase;
}
.meta strong {
  color: var(--ink);
  font-weight: 500;
}

/* body */
.layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 48px;
  padding: 64px 0 120px;
}
.toc {
  display: none;
}
.toc ol {
  list-style: none;
  border-top: 1px solid var(--line);
}
.toc a {
  display: flex;
  gap: 14px;
  padding: 11px 0;
  border-bottom: 1px solid var(--line);
  text-decoration: none;
  color: var(--muted);
  font-size: 14px;
  transition: color 0.2s;
}
.toc a span {
  font-family: var(--mono);
  font-size: 11px;
  padding-top: 3px;
}
.toc a:hover,
.toc a.on {
  color: var(--ink);
}
.toc a.on span {
  color: var(--accent);
}
.doc {
  max-width: 760px;
}
.card {
  background: var(--ink);
  color: var(--paper);
  border-radius: 24px;
  padding: 28px;
  margin-bottom: 56px;
  display: grid;
  gap: 18px;
}
.card .k {
  font-family: var(--mono);
  font-size: 11px;
  text-transform: uppercase;
  color: var(--muted-dark);
  margin-bottom: 4px;
}
.card .v {
  font-size: 17px;
  line-height: 1.5;
}
.card a {
  color: var(--accent);
  text-decoration: none;
}
.sec {
  padding: 36px 0;
  border-top: 1px solid var(--line);
  scroll-margin-top: 90px;
}
.sec:first-of-type {
  border-top: none;
  padding-top: 0;
}
.sec h2 {
  font-family: var(--display);
  font-weight: 500;
  font-size: clamp(24px, 2.6vw, 34px);
  letter-spacing: -0.025em;
  line-height: 1.1;
  margin-bottom: 18px;
  display: flex;
  gap: 16px;
  align-items: baseline;
}
.sec h2 .n {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--accent);
  letter-spacing: 0;
  flex-shrink: 0;
}
.sec p,
.sec li {
  font-size: 16.5px;
  color: var(--ink-3);
  line-height: 1.7;
}
.sec p + p,
.sec p + ul,
.sec ul + p {
  margin-top: 14px;
}
.sec ul {
  list-style: none;
  display: grid;
  gap: 8px;
}
.sec li {
  display: flex;
  gap: 12px;
}
.sec li::before {
  content: "→";
  color: var(--accent);
  flex-shrink: 0;
}
.sec strong {
  color: var(--ink);
  font-weight: 700;
}
.sec a {
  color: var(--ink);
  text-decoration: underline;
  text-decoration-color: var(--accent);
  text-underline-offset: 3px;
}
.facts {
  display: grid;
  grid-template-columns: 1fr;
  border: 1px solid var(--line);
  border-radius: 18px;
  overflow: hidden;
  margin-top: 18px;
}
.facts div {
  padding: 16px 18px;
  border-bottom: 1px solid var(--line);
  background: #fbf9f5;
}
.facts div:last-child {
  border-bottom: none;
}
.facts dt {
  font-family: var(--mono);
  font-size: 11px;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 4px;
}
.facts dd {
  font-size: 15px;
  color: var(--ink-3);
}

/* footer */
footer {
  background: var(--ink);
  color: var(--paper);
  overflow: hidden;
}
.foot {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 20px;
  padding: 48px 0 28px;
}
.foot-links {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}
.foot a {
  color: var(--paper-3);
  text-decoration: none;
  font-size: 15px;
}
.foot a:hover {
  color: var(--accent);
}
.foot .copy {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--muted-dark);
  text-transform: uppercase;
}
.wordmark {
  font-family: var(--display);
  font-weight: 600;
  font-size: 30.5vw;
  line-height: 0.8;
  letter-spacing: -0.065em;
  text-align: center;
  white-space: nowrap;
  user-select: none;
  padding-bottom: 0.04em;
}
.wordmark i {
  font-style: normal;
  color: var(--accent);
}

@media (min-width: 760px) {
  :root {
    --px: 32px;
  }
  .card {
    grid-template-columns: 1fr 1fr;
    padding: 32px 36px;
  }
  .facts {
    grid-template-columns: 1fr 1fr;
  }
  .facts div:nth-child(odd) {
    border-right: 1px solid var(--line);
  }
  .facts div:nth-last-child(-n + 2) {
    border-bottom: none;
  }
}
@media (min-width: 1080px) {
  :root {
    --px: 48px;
  }
  .layout {
    grid-template-columns: 300px 1fr;
    gap: 96px;
  }
  .toc {
    display: block;
    position: sticky;
    top: 100px;
    align-self: start;
  }
  .toc .label {
    margin-bottom: 16px;
  }
}