:root {
  --ink: #18201d;
  --muted: #5d6964;
  --line: #dfe6e2;
  --paper: #ffffff;
  --soft: #f4f7f5;
  --mint: #1f9d73;
  --mint-dark: #12684d;
  --coral: #df6a55;
  --blue: #356fd6;
  --shadow: 0 18px 45px rgba(25, 42, 35, 0.09);
  font-family: Inter, "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  color: var(--ink);
  background: var(--paper);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; line-height: 1.7; background: var(--paper); }
a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }
.shell { width: min(1180px, calc(100% - 40px)); margin: 0 auto; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid rgba(223, 230, 226, 0.88);
  background: rgba(255,255,255,0.94);
  backdrop-filter: blur(16px);
}
.header-inner { min-height: 70px; display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.brand { display: flex; align-items: center; gap: 11px; }
.brand-mark {
  width: 38px; height: 38px; display: grid; place-items: center;
  background: var(--ink); color: white; font-size: 13px; font-weight: 800;
  border-radius: 6px;
}
.brand span:last-child { display: flex; flex-direction: column; line-height: 1.25; }
.brand strong { font-size: 16px; }
.brand small { color: var(--muted); }
nav { display: flex; align-items: center; gap: 26px; font-size: 14px; }
nav a:hover { color: var(--mint-dark); }
.nav-contact { border: 1px solid var(--ink); padding: 7px 13px; border-radius: 6px; }

.hero { min-height: 620px; position: relative; overflow: hidden; display: grid; align-items: center; }
.hero > img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; object-position: center; }
.hero-shade { position: absolute; inset: 0; background: rgba(255,255,255,.68); }
.hero-content { position: relative; padding: 88px 0 110px; }
.eyebrow { margin: 0 0 12px; color: var(--mint-dark); font-size: 12px; font-weight: 800; letter-spacing: 0; }
.hero h1 { max-width: 660px; margin: 0; font-size: 72px; line-height: 1.08; letter-spacing: 0; }
.hero-lead { margin: 20px 0 0; font-size: 24px; font-weight: 700; }
.hero-copy { max-width: 560px; margin: 15px 0 0; color: #44504b; font-size: 17px; }
.hero-actions { display: flex; gap: 12px; margin-top: 30px; flex-wrap: wrap; }
.button { display: inline-flex; min-height: 46px; align-items: center; justify-content: center; padding: 0 20px; border: 1px solid var(--ink); border-radius: 6px; font-weight: 700; }
.button.primary { color: white; background: var(--ink); }
.button.secondary { background: rgba(255,255,255,.86); }
.button:hover { transform: translateY(-1px); }

.signal-band { border-block: 1px solid var(--line); background: var(--soft); }
.signal-grid { display: grid; grid-template-columns: repeat(3, 1fr); }
.signal-grid div { padding: 24px 30px; border-right: 1px solid var(--line); }
.signal-grid div:first-child { padding-left: 0; }
.signal-grid div:last-child { border-right: 0; }
.signal-grid strong, .signal-grid span { display: block; }
.signal-grid span { color: var(--muted); font-size: 14px; }

.section { padding: 92px 0; }
.section-heading { display: flex; justify-content: space-between; align-items: end; gap: 30px; margin-bottom: 34px; }
.section-heading h2, .compare-layout h2, .faq-preview h2 { margin: 0; font-size: 34px; line-height: 1.25; }
.section-heading > p { max-width: 440px; margin: 0; color: var(--muted); }
.guide-grid { display: grid; grid-template-columns: repeat(3, 1fr); border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.guide-card { min-width: 0; padding: 28px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); background: var(--paper); }
.guide-card:hover { box-shadow: var(--shadow); position: relative; z-index: 1; }
.guide-meta { display: flex; justify-content: space-between; gap: 16px; color: var(--muted); font-size: 12px; }
.guide-meta span { color: var(--mint-dark); font-weight: 800; }
.guide-card h2 { margin: 18px 0 10px; font-size: 22px; line-height: 1.38; }
.guide-card p { margin: 0; color: var(--muted); font-size: 14px; }
.read-link { display: inline-flex; gap: 8px; margin-top: 20px; color: var(--blue); font-weight: 700; font-size: 14px; }

.compare-band { padding: 88px 0; color: white; background: var(--ink); }
.compare-layout { display: grid; grid-template-columns: .9fr 1.1fr; gap: 90px; align-items: start; }
.compare-layout > div:first-child > p:last-child { color: #b9c5c0; }
.compare-list { border-top: 1px solid #42504a; }
.compare-list div { display: grid; grid-template-columns: 130px 1fr; gap: 30px; padding: 21px 0; border-bottom: 1px solid #42504a; }
.compare-list span { color: #c9d2ce; }
.faq-preview { display: flex; justify-content: space-between; gap: 50px; align-items: center; }
.faq-preview > div:first-child { max-width: 680px; }
.faq-preview > div:first-child > p:last-child { color: var(--muted); }
.help-actions { display: flex; flex-direction: column; align-items: start; gap: 16px; }
.text-link { color: var(--blue); font-weight: 700; }

.article-main { background: var(--soft); }
.article-shell { padding-top: 32px; padding-bottom: 90px; }
.breadcrumb { justify-content: flex-start; gap: 9px; color: var(--muted); font-size: 13px; }
.article { margin-top: 24px; background: var(--paper); border: 1px solid var(--line); }
.article-header { max-width: 900px; padding: 70px 70px 48px; }
.article-header h1 { margin: 18px 0; font-size: 58px; line-height: 1.15; }
.article-header > p { color: var(--muted); font-size: 18px; }
.article-layout { display: grid; grid-template-columns: 260px minmax(0, 720px); gap: 70px; padding: 0 70px 80px; }
.toc { position: sticky; top: 100px; align-self: start; display: flex; flex-direction: column; gap: 10px; padding-top: 12px; font-size: 14px; }
.toc strong { margin-bottom: 5px; }
.toc a { color: var(--muted); border-left: 2px solid var(--line); padding-left: 12px; }
.toc a:hover { color: var(--mint-dark); border-color: var(--mint); }
.article-content { min-width: 0; }
.article-intro { padding: 22px 24px; border-left: 4px solid var(--coral); background: #fff7f4; font-size: 17px; }
.article-content section { scroll-margin-top: 95px; padding-top: 34px; }
.article-content h2 { margin: 0 0 14px; font-size: 28px; }
.article-content p { color: #3f4a46; }
.service-note { margin-top: 48px; padding: 28px; border: 1px solid #b8ddd0; background: #f1faf7; }
.service-note h2 { font-size: 23px; }
.service-note p { margin: 8px 0; }
.service-note a { color: var(--blue); font-weight: 700; overflow-wrap: anywhere; }
.related { padding-top: 70px; }
.guide-grid.compact .guide-card { padding: 24px; }

.site-footer { padding: 56px 0 24px; border-top: 1px solid var(--line); background: #f8faf9; }
.footer-grid { display: grid; grid-template-columns: 1.5fr repeat(3, 1fr); gap: 44px; }
.footer-grid p { color: var(--muted); max-width: 360px; }
.footer-grid > div:not(:first-child) { display: flex; flex-direction: column; }
.footer-grid span { color: var(--muted); font-size: 13px; }
.footer-grid a { margin-top: 8px; font-weight: 700; overflow-wrap: anywhere; }
.copyright { margin-top: 35px; padding-top: 20px; border-top: 1px solid var(--line); color: var(--muted); font-size: 12px; }

@media (max-width: 900px) {
  nav a:not(.nav-contact) { display: none; }
  .hero { min-height: 590px; align-items: end; }
  .hero > img { object-position: 68% center; }
  .hero-shade { background: rgba(255,255,255,.78); }
  .hero-content { padding: 210px 0 58px; }
  .hero h1 { font-size: 48px; }
  .article-header h1 { font-size: 46px; }
  .signal-grid, .guide-grid { grid-template-columns: 1fr; }
  .signal-grid div { border-right: 0; border-bottom: 1px solid var(--line); padding-left: 0; }
  .compare-layout { grid-template-columns: 1fr; gap: 40px; }
  .article-header { padding: 46px 28px 30px; }
  .article-layout { display: block; padding: 0 28px 50px; }
  .toc { position: static; padding: 18px; background: var(--soft); margin-bottom: 22px; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 620px) {
  .shell { width: min(100% - 28px, 1180px); }
  .header-inner { min-height: 62px; }
  .brand-mark { width: 34px; height: 34px; }
  .nav-contact { padding: 6px 10px; }
  .hero { min-height: 640px; }
  .hero-content { padding-top: 260px; }
  .hero h1 { font-size: 42px; }
  .hero-lead { font-size: 20px; }
  .section { padding: 68px 0; }
  .section-heading, .faq-preview { display: block; }
  .section-heading h2, .compare-layout h2, .faq-preview h2 { font-size: 29px; }
  .section-heading > p { margin-top: 12px; }
  .guide-card { padding: 23px; }
  .compare-list div { grid-template-columns: 1fr; gap: 3px; }
  .help-actions { margin-top: 24px; }
  .article-shell { width: 100%; padding-top: 18px; }
  .breadcrumb { padding-inline: 14px; }
  .article { border-inline: 0; }
  .article-header h1 { font-size: 38px; }
  .article-header > p { font-size: 16px; }
  .article-content h2 { font-size: 25px; }
  .related { padding-inline: 14px; }
  .footer-grid { grid-template-columns: 1fr; gap: 26px; }
}