:root {
  --paper: #eef2f8;
  --ink: #172033;
  --muted: #526178;
  --line: #d5deea;
  --brand: #5b6fe8;
  --sheet: #f7f9fc;
}

* { box-sizing: border-box; }

html { scroll-behavior: auto; }

body {
  margin: 0;
  min-height: 100vh;
  background: var(--paper);
  color: var(--ink);
  font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.7;
}

body::before {
  content: "";
  position: fixed;
  left: 0;
  top: 0;
  bottom: 0;
  width: 8px;
  background: var(--brand);
}

a { color: var(--brand); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: #3d52c9; }

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

.wrap {
  width: min(720px, calc(100% - 48px));
  margin: 0 auto;
}

header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 28px 0 8px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  text-decoration: none;
  font-family: "Songti SC", "STSong", "Noto Serif SC", serif;
  font-size: 22px;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.brand img { width: 28px; height: 28px; display: block; }

nav { display: flex; gap: 18px; flex-wrap: wrap; }

nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 15px;
}

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

main { padding: 36px 0 64px; }

h1 {
  margin: 0;
  font-family: "Songti SC", "STSong", "Noto Serif SC", serif;
  font-size: clamp(52px, 9vw, 84px);
  font-weight: 700;
  line-height: 1.05;
  letter-spacing: 0.02em;
}

.slogan {
  margin: 14px 0 0;
  font-family: "Songti SC", "STSong", "Noto Serif SC", serif;
  font-size: 22px;
  line-height: 1.45;
}

.lead {
  margin: 22px 0 0;
  max-width: 38em;
  color: var(--muted);
}

h2 {
  margin: 48px 0 12px;
  font-size: 20px;
  font-weight: 700;
  line-height: 1.4;
}

.facts {
  margin: 28px 0 0;
  padding: 8px 0 0;
  border-top: 1px solid var(--line);
}

.facts div {
  display: grid;
  grid-template-columns: 9em 1fr;
  gap: 12px;
  padding: 12px 0;
  border-bottom: 1px solid var(--line);
}

.facts dt { margin: 0; color: var(--muted); }
.facts dd { margin: 0; }

.steps { margin: 0; padding: 0; list-style: none; }
.steps li { padding: 14px 0 14px 16px; border-left: 2px solid var(--line); }
.steps strong { display: block; color: var(--ink); font-weight: 700; }
.steps span { color: var(--muted); }

.doc h1 { font-size: clamp(36px, 6vw, 52px); }
.doc h2 { margin-top: 28px; font-size: 17px; }
.doc p { margin: 8px 0 0; color: var(--muted); }

footer {
  padding: 28px 0 40px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 13px;
  line-height: 1.8;
}

footer p { margin: 0; }
footer a { color: var(--muted); }
footer a:hover { color: var(--brand); }

@media (max-width: 640px) {
  body::before { width: 100%; height: 4px; bottom: auto; }
  .wrap { width: min(720px, calc(100% - 32px)); }
  header { align-items: flex-start; flex-direction: column; gap: 12px; padding-top: 22px; }
  .facts div { grid-template-columns: 1fr; gap: 2px; }
}