:root {
  color-scheme: light;
  --ink: #17324d;
  --muted: #5b6d7e;
  --line: #dbe7ef;
  --blue: #0867c7;
  --blue-dark: #064c91;
  --blue-soft: #eef7ff;
  --green-soft: #effaf4;
  --paper: #ffffff;
  --canvas: #f5f9fc;
}

* { box-sizing: border-box; }
body { margin: 0; color: var(--ink); background: var(--canvas); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif; line-height: 1.72; }
a { color: var(--blue); }
.site-header { min-height: 68px; padding: 0 5vw; display: flex; align-items: center; justify-content: space-between; gap: 24px; background: var(--paper); border-bottom: 1px solid var(--line); }
.brand { display: inline-flex; align-items: center; gap: 10px; color: var(--blue-dark); font-size: 1.12rem; font-weight: 750; text-decoration: none; }
.brand img { width: auto; height: 42px; max-width: 160px; object-fit: contain; }
.product-id { color: var(--muted); font-size: .88rem; }
main { width: min(920px, calc(100% - 32px)); margin: 32px auto 64px; }
article { padding: clamp(24px, 5vw, 64px); background: var(--paper); border: 1px solid var(--line); border-radius: 20px; box-shadow: 0 18px 50px rgba(28, 70, 102, .08); }
.breadcrumb { display: flex; gap: 8px; color: var(--muted); font-size: .88rem; }
.hero { padding: 44px 0 18px; }
.eyebrow { margin: 0 0 10px; color: var(--blue); font-size: .82rem; font-weight: 750; letter-spacing: .08em; }
h1, h2, h3 { line-height: 1.25; }
h1 { margin: 0; font-size: clamp(2rem, 5vw, 3.25rem); letter-spacing: -.035em; }
h2 { margin-top: 48px; font-size: clamp(1.45rem, 3vw, 2rem); }
h3 { margin-top: 0; }
.answer { max-width: 760px; margin: 24px 0; color: #314d66; font-size: 1.08rem; }
.boundary { margin: 28px 0 0; padding: 20px 22px; background: #fff8e8; border-left: 4px solid #e49b18; border-radius: 8px; }
.boundary p { margin: 5px 0 0; }
.steps { padding: 0; list-style: none; counter-reset: step; }
.steps li { counter-increment: step; position: relative; margin: 12px 0; padding: 18px 18px 18px 62px; display: grid; gap: 3px; background: var(--blue-soft); border: 1px solid #cfe5f7; border-radius: 12px; }
.steps li::before { content: counter(step); position: absolute; top: 18px; left: 18px; width: 30px; height: 30px; display: grid; place-items: center; color: #fff; background: var(--blue); border-radius: 50%; font-weight: 750; }
.steps span { color: #405970; }
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; }
th, td { padding: 13px 16px; text-align: left; border-bottom: 1px solid var(--line); }
th { width: 33%; color: var(--muted); font-size: .88rem; }
.note { padding: 14px 16px; color: #314d66; background: #f1f6fa; border-radius: 8px; }
.example { margin-top: 48px; padding: clamp(22px, 4vw, 34px); background: var(--blue-soft); border: 1px solid #c9e2f7; border-radius: 16px; }
.example h2 { margin-top: 0; }
.metric-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.metric-grid div { padding: 18px; display: grid; gap: 6px; background: #fff; border-radius: 10px; }
.metric-grid span { color: var(--muted); font-size: .84rem; }
.metric-grid strong { color: var(--blue-dark); font-size: 1.15rem; line-height: 1.35; }
.metric-grid small { color: var(--muted); }
.facts { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); margin: 24px 0; }
.facts div { padding: 14px; border-top: 1px solid var(--line); }
.facts dt { color: var(--muted); font-size: .82rem; }
.facts dd { margin: 4px 0 0; font-weight: 650; }
.button { display: inline-block; padding: 12px 18px; color: #fff; background: var(--blue); border-radius: 8px; font-weight: 700; text-decoration: none; }
.two-column > div { margin-top: 14px; padding: 22px; background: var(--green-soft); border-radius: 12px; }
.two-column > div:last-child { background: #f8f3f3; }
.two-column ul, .questions { padding-left: 20px; }
.questions li { margin: 8px 0; }
details { padding: 15px 0; border-bottom: 1px solid var(--line); }
summary { cursor: pointer; font-weight: 700; }
details p { color: #405970; }
.article-footer { margin-top: 48px; padding-top: 20px; color: var(--muted); font-size: .86rem; border-top: 1px solid var(--line); }
.article-footer p { margin: 4px 0; }

@media (max-width: 680px) {
  .site-header { padding: 10px 16px; }
  .brand span { display: none; }
  main { width: min(100% - 20px, 920px); margin-top: 10px; }
  article { padding: 22px; border-radius: 14px; }
  .hero { padding-top: 32px; }
  .metric-grid, .facts { grid-template-columns: 1fr; }
  th { width: 42%; }
}