:root {
  --ink: #182230;
  --ink-soft: #536171;
  --paper: #f6f8fb;
  --card: #ffffff;
  --line: #dfe5ec;
  --brand: #f45d35;
  --brand-deep: #c84220;
  --navy: #121c2b;
  --navy-soft: #20324a;
  --accent-soft: #fff0ea;
  --focus: #1258a7;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.75;
}
a { color: var(--brand-deep); text-underline-offset: 3px; }
a:hover { color: var(--brand); }
a:focus-visible { outline: 3px solid var(--focus); outline-offset: 3px; border-radius: 4px; }
img { display: block; max-width: 100%; }
.shell { width: min(1120px, calc(100% - 40px)); margin: 0 auto; }
.narrow { max-width: 800px; }

.site-header { background: var(--navy); color: #fff; border-bottom: 1px solid rgba(255, 255, 255, .1); }
.header-inner { min-height: 72px; display: flex; align-items: center; justify-content: space-between; gap: 28px; }
.brand { display: inline-flex; align-items: center; gap: 11px; color: #fff; text-decoration: none; }
.brand img { width: 36px; height: 36px; border-radius: 50%; }
.brand span { display: grid; line-height: 1.2; }
.brand strong { font-size: 17px; }
.brand small { margin-top: 3px; color: #aebdd0; font-size: 12px; }
.site-header nav { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 18px; }
.site-header nav a { color: #d9e3ee; font-size: 14px; text-decoration: none; }
.site-header nav a:hover { color: #fff; }

.breadcrumb { display: flex; flex-wrap: wrap; gap: 8px; padding: 24px 0 0; color: #738092; font-size: 13px; }
.breadcrumb a { color: #5b6878; text-decoration: none; }
.page-shell, .article-shell { padding-bottom: 64px; }
.page-hero, .article-header { padding: 46px 0 34px; }
.page-hero { max-width: 800px; }
.page-hero h1, .article-header h1 { margin: 0; max-width: 900px; font-size: clamp(32px, 6vw, 54px); line-height: 1.14; letter-spacing: -.035em; }
.page-hero > p:not(.eyebrow), .dek { margin: 22px 0 0; max-width: 760px; color: var(--ink-soft); font-size: 18px; line-height: 1.75; }
.eyebrow { margin: 0 0 10px; color: var(--brand-deep); font-size: 13px; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; }
.updated { font-size: 14px !important; }

.article { max-width: 820px; }
.article-header { padding-bottom: 24px; }
.article-header h1 { font-size: clamp(30px, 5vw, 48px); }
.article-meta { display: flex; flex-wrap: wrap; gap: 8px 18px; margin-top: 22px; color: #6a7787; font-size: 13px; }
.toc { margin: 12px 0 30px; padding: 20px 24px; background: #eef2f7; border-left: 4px solid #b7c3d1; border-radius: 0 10px 10px 0; }
.toc strong { display: block; margin-bottom: 8px; }
.toc ol { margin: 0; padding-left: 20px; columns: 2; }
.toc li { break-inside: avoid; margin: 3px 24px 3px 0; }
.toc a { color: #405063; text-decoration: none; }

.article-body { padding: 38px clamp(22px, 5vw, 64px) 44px; background: var(--card); border: 1px solid var(--line); border-radius: 16px; box-shadow: 0 14px 42px rgba(24, 34, 48, .06); }
.article-body > :first-child { margin-top: 0; }
.article-body h2 { margin: 50px 0 14px; font-size: 26px; line-height: 1.35; }
.article-body h3 { margin: 34px 0 10px; font-size: 20px; line-height: 1.4; }
.article-body p { margin: 0 0 19px; }
.article-body ul, .article-body ol, .prose-section ul { margin: 0 0 24px; padding-left: 24px; }
.article-body li, .prose-section li { margin-bottom: 8px; }
.article-body hr { margin: 38px 0; border: 0; border-top: 1px solid var(--line); }
.article-body code { padding: 2px 5px; background: #edf1f5; border-radius: 4px; font-size: .92em; }

.safety-note { margin-top: 20px; padding: 20px 24px; background: #fff8e8; border: 1px solid #ead9a8; border-radius: 12px; color: #51482d; }
.safety-note p { margin: 7px 0; font-size: 14px; }
.safety-note a { font-size: 14px; }
.product-cta { display: flex; align-items: center; justify-content: space-between; gap: 28px; margin-top: 20px; padding: 28px; color: #fff; background: linear-gradient(135deg, var(--navy), var(--navy-soft)); border-radius: 14px; }
.product-cta .eyebrow { color: #ffbda8; }
.product-cta h2 { margin: 0; font-size: 25px; }
.product-cta p { margin: 6px 0 0; color: #cbd6e2; }
.button { display: inline-flex; min-height: 46px; align-items: center; justify-content: center; flex: none; padding: 0 19px; color: #fff; background: var(--brand); border-radius: 999px; font-weight: 700; text-decoration: none; }
.button:hover { color: #fff; background: #ff744e; }

.guide-section, .related { padding: 34px 0 12px; }
.related { max-width: 100%; margin-top: 32px; }
.section-heading { margin-bottom: 18px; }
.section-heading h2 { margin: 0; max-width: 700px; font-size: 28px; line-height: 1.3; }
.card-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 15px; }
.guide-card { display: block; min-height: 100%; padding: 22px; color: var(--ink); background: var(--card); border: 1px solid var(--line); border-radius: 12px; text-decoration: none; transition: transform .18s ease, border-color .18s ease, box-shadow .18s ease; }
.guide-card:hover { color: var(--ink); border-color: #c7d0db; box-shadow: 0 12px 30px rgba(24, 34, 48, .08); transform: translateY(-2px); }
.guide-card span { display: block; margin-bottom: 8px; color: var(--brand-deep); font-size: 12px; font-weight: 800; }
.guide-card strong { display: block; font-size: 18px; line-height: 1.45; }
.guide-card p { margin: 10px 0 0; color: var(--ink-soft); font-size: 14px; line-height: 1.65; }

.prose-section { margin-bottom: 18px; padding: 28px 32px; background: var(--card); border: 1px solid var(--line); border-radius: 13px; }
.prose-section h2 { margin: 0 0 12px; font-size: 24px; }
.prose-section p { margin: 0 0 14px; }
.prose-section p:last-child { margin-bottom: 0; }
.facts { margin: 0; }
.facts > div { display: grid; grid-template-columns: minmax(120px, .7fr) 2fr; gap: 18px; padding: 14px 0; border-bottom: 1px solid var(--line); }
.facts > div:last-child { border-bottom: 0; }
.facts dt { font-weight: 800; }
.facts dd { margin: 0; color: var(--ink-soft); }

.answer-box { margin: 0 0 28px; padding: 28px 32px; color: #fff; background: linear-gradient(135deg, var(--navy), var(--navy-soft)); border-radius: 14px; }
.answer-box .eyebrow { color: #ffbda8; }
.answer-box h2 { margin: 0; font-size: clamp(23px, 4vw, 31px); line-height: 1.35; }
.answer-box p:last-child { margin: 12px 0 0; color: #e0e7ef; font-size: 17px; }
.topic-layout { display: grid; grid-template-columns: minmax(0, 1fr) 250px; align-items: start; gap: 24px; }
.topic-aside { position: sticky; top: 20px; display: grid; gap: 9px; padding: 22px; background: #eef2f7; border: 1px solid var(--line); border-radius: 12px; }
.topic-aside strong { margin-bottom: 3px; }
.topic-aside a { font-size: 14px; text-decoration: none; }
.topic-index { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.topic-intro { margin-top: 28px; }
.table-wrap { max-width: 100%; margin: 18px 0 6px; overflow-x: auto; border: 1px solid var(--line); border-radius: 10px; }
.table-wrap:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; }
table { width: 100%; min-width: 620px; border-collapse: collapse; background: #fff; font-size: 14px; line-height: 1.55; }
th, td { padding: 13px 14px; text-align: left; vertical-align: top; border-bottom: 1px solid var(--line); }
thead th { color: #fff; background: var(--navy-soft); font-size: 13px; }
tbody th { width: 18%; background: #f6f8fb; }
tbody tr:last-child th, tbody tr:last-child td { border-bottom: 0; }
.faq-section { margin-top: 34px; }
.faq-section details { margin-bottom: 10px; background: var(--card); border: 1px solid var(--line); border-radius: 10px; }
.faq-section summary { padding: 16px 20px; cursor: pointer; font-weight: 750; }
.faq-section details p { margin: 0; padding: 0 20px 18px; color: var(--ink-soft); }
.faq-long article { margin-bottom: 12px; padding: 22px 26px; background: var(--card); border: 1px solid var(--line); border-radius: 11px; }
.faq-long article h2 { margin: 0; font-size: 20px; line-height: 1.45; }
.faq-long article p { margin: 8px 0 0; color: var(--ink-soft); }
.steps { margin: 0; padding-left: 23px; }
.steps li { margin-bottom: 12px; }

.site-footer { padding: 42px 0 26px; color: #aebdd0; background: var(--navy); }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr; gap: 30px; }
.footer-grid strong { color: #fff; font-size: 18px; }
.footer-grid p { max-width: 620px; margin: 8px 0 0; }
.footer-grid > div:last-child { display: grid; align-content: start; gap: 6px; }
.footer-grid a { color: #dce5ef; font-size: 14px; text-decoration: none; }
.legal { margin-top: 28px; padding-top: 18px; border-top: 1px solid rgba(255, 255, 255, .12); font-size: 12px; }

@media (max-width: 820px) {
  .header-inner { align-items: flex-start; flex-direction: column; padding: 15px 0; }
  .site-header nav { justify-content: flex-start; gap: 8px 16px; }
  .card-grid { grid-template-columns: 1fr 1fr; }
  .product-cta { align-items: flex-start; flex-direction: column; }
  .topic-layout { grid-template-columns: 1fr; }
  .topic-aside { position: static; }
}

@media (max-width: 560px) {
  .shell { width: min(100% - 28px, 1120px); }
  .page-hero, .article-header { padding: 34px 0 24px; }
  .page-hero > p:not(.eyebrow), .dek { font-size: 16px; }
  .article-body { padding: 28px 20px 34px; }
  .article-body h2 { margin-top: 38px; font-size: 23px; }
  .toc ol { columns: 1; }
  .card-grid { grid-template-columns: 1fr; }
  .prose-section { padding: 23px 20px; }
  .facts > div { grid-template-columns: 1fr; gap: 4px; }
  .answer-box { padding: 24px 20px; }
  .topic-index { grid-template-columns: 1fr; }
  .faq-long article { padding: 20px; }
  .footer-grid { grid-template-columns: 1fr; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .guide-card { transition: none; }
}