:root {
  --ink: #1b1b1f;
  --muted: #5b616e;
  --line: #e3e6ec;
  --accent: #1a5cff;
  --bg: #ffffff;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.7;
}

.site-header {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: baseline;
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--line);
}

.brand { font-weight: 700; font-size: 1.125rem; }
.tag { color: var(--muted); font-size: 0.875rem; }

main { max-width: 46rem; margin: 0 auto; padding: 0 1.5rem 3rem; }

section { padding: 1.75rem 0; border-bottom: 1px solid var(--line); }
section:last-of-type { border-bottom: 0; }

h1 { font-size: 1.75rem; line-height: 1.35; margin: 1.5rem 0 0.75rem; }
h2 { font-size: 1.25rem; margin: 0 0 0.75rem; }
h3 { font-size: 1rem; margin: 0 0 0.35rem; }

.lead { color: #33363d; }
.fineprint, .placeholder { color: var(--muted); font-size: 0.8125rem; }

.cta { margin: 1.25rem 0 0.5rem; }

.button {
  display: inline-block;
  padding: 0.65rem 1.15rem;
  border-radius: 999px;
  background: var(--accent);
  color: #fff;
  text-decoration: none;
  font-weight: 600;
}

.cards { list-style: none; margin: 0; padding: 0; display: grid; gap: 1rem; grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr)); }
.cards li { border: 1px solid var(--line); border-radius: 12px; padding: 1rem; }
.cards p { margin: 0; color: var(--muted); font-size: 0.9375rem; }

.steps { margin: 0; padding-left: 1.25rem; }
.steps li { margin-bottom: 0.5rem; }

details { border-top: 1px solid var(--line); padding: 0.6rem 0; }
details:first-of-type { border-top: 0; }
summary { cursor: pointer; font-weight: 600; }
details p { margin: 0.5rem 0 0; color: var(--muted); }

.site-footer {
  border-top: 1px solid var(--line);
  padding: 1.5rem;
  color: var(--muted);
  font-size: 0.8125rem;
  max-width: 46rem;
  margin: 0 auto;
}