:root {
  color-scheme: light;
  --ink: #101828;
  --muted: #52617a;
  --line: #dce4f2;
  --paper: #ffffff;
  --wash: #f4f7fb;
  --blue: #1677e8;
  --blue-dark: #0755ad;
  --blue-soft: #e7f2ff;
  --danger: #b42318;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background:
    radial-gradient(circle at 10% 0%, rgba(22, 119, 232, .14), transparent 28rem),
    radial-gradient(circle at 92% 14%, rgba(87, 71, 237, .11), transparent 25rem),
    var(--wash);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans TC",
    "PingFang HK", "Microsoft JhengHei", sans-serif;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--blue-dark); text-underline-offset: .18em; }

.frame { min-height: 100vh; }

.bar, main, footer {
  width: min(900px, calc(100% - 40px));
  margin-inline: auto;
}

.bar {
  min-height: 84px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: var(--ink);
  font-size: 1.1rem;
  font-weight: 850;
  text-decoration: none;
}

.mark {
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  border-radius: 13px;
  background: linear-gradient(145deg, #31a9ff, #4f46e5);
  color: #fff;
  font-size: 23px;
  font-weight: 900;
  box-shadow: 0 8px 24px rgba(27, 35, 68, .15);
}

nav, footer div { display: flex; gap: 18px; }
nav a { color: var(--muted); font-weight: 750; text-decoration: none; }
nav a:hover { color: var(--blue-dark); }

.doc {
  margin: 30px auto 70px;
  padding: clamp(28px, 6vw, 68px);
  border: 1px solid var(--line);
  border-radius: 32px;
  background: rgba(255, 255, 255, .97);
  box-shadow: 0 24px 70px rgba(36, 47, 84, .1);
}

.head { padding-bottom: 30px; border-bottom: 1px solid var(--line); }
.eyebrow {
  display: inline-flex;
  padding: 7px 12px;
  border-radius: 999px;
  background: var(--blue-soft);
  color: var(--blue-dark);
  font-size: .78rem;
  font-weight: 900;
  letter-spacing: .12em;
}

.head h1 {
  margin: 18px 0 14px;
  font-size: clamp(2.25rem, 7vw, 4.4rem);
  line-height: 1.07;
  letter-spacing: -.05em;
}

.head p { margin: 0; max-width: 710px; color: var(--muted); font-size: 1.04rem; }
.doc section { padding-top: 27px; }
.doc h2 { margin: 0 0 9px; font-size: 1.25rem; letter-spacing: -.02em; }
.doc p, .doc li { color: #46546c; }
.doc ul, .doc ol { padding-left: 1.3rem; }
.doc li + li { margin-top: 8px; }

.notice {
  margin-top: 27px;
  padding: 18px 20px;
  border: 1px solid #b8d6fb;
  border-radius: 18px;
  background: var(--blue-soft);
}

.notice.warning { border-color: #f2c7c2; background: #fff1f0; }
.notice.warning strong { color: var(--danger); }
.notice p { margin: 4px 0 0; }

.button {
  display: inline-flex;
  min-height: 50px;
  align-items: center;
  justify-content: center;
  margin-top: 10px;
  padding: 12px 20px;
  border-radius: 15px;
  background: linear-gradient(135deg, var(--blue), #5548ed);
  color: #fff;
  font-weight: 850;
  text-decoration: none;
  box-shadow: 0 12px 28px rgba(22, 119, 232, .24);
}

.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; margin-top: 26px; }
.card { padding: 20px; border: 1px solid var(--line); border-radius: 19px; background: #fff; }
.card h2 { margin-top: 0; }

footer {
  display: flex;
  justify-content: space-between;
  gap: 24px;
  padding: 26px 0 42px;
  color: var(--muted);
  font-size: .9rem;
}

footer p { margin: 0; }

@media (max-width: 720px) {
  .bar, main, footer { width: min(100% - 24px, 900px); }
  .bar { min-height: 72px; }
  nav { gap: 12px; font-size: .87rem; }
  .doc { margin-top: 16px; border-radius: 24px; }
  .cards { grid-template-columns: 1fr; }
  footer { flex-direction: column; }
}

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