:root {
  --bg: #f2f4f6;
  --surface: #ffffff;
  --surface-alt: #e7ecef;
  --ink: #141a20;
  --muted: #5a6671;
  --line: rgba(20, 26, 32, 0.12);
  --brand: #234d66;
  --brand-2: #1f6b47;
  --danger: #b84b3c;
  --warn: #a7701e;
  --shadow: 0 18px 42px rgba(20, 26, 32, 0.08);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: linear-gradient(180deg, #121923 0%, #121923 460px, var(--bg) 460px, var(--bg) 100%);
  color: var(--ink);
  font: 16px/1.6 "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  overflow-x: hidden;
}
img { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
.container { width: min(1180px, calc(100% - 32px)); margin: 0 auto; }
.skip-link {
  position: absolute; left: 16px; top: 8px; z-index: 1000; padding: 10px 14px; background: #fff; border-radius: 999px;
  transform: translateY(-180%); transition: transform .2s ease;
}
.skip-link:focus { transform: translateY(0); }
.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0;
}

.site-header {
  position: sticky; top: 0; z-index: 80; background: rgba(18,25,35,.88); backdrop-filter: blur(14px);
  border-bottom: 1px solid rgba(255,255,255,.08);
}
.header-inner {
  min-height: 74px; display: flex; align-items: center; justify-content: space-between; gap: 16px; color: #fff;
}
.brand-wordmark { height: 28px; width: auto; }
.header-tag {
  padding: 7px 12px; border-radius: 999px; background: rgba(255,255,255,.08); font-size: 13px; color: rgba(255,255,255,.82);
}
.menu-toggle { display: none; border: 0; background: transparent; padding: 10px; cursor: pointer; }
.menu-toggle span { display: block; width: 24px; height: 2px; margin: 4px 0; background: #fff; border-radius: 999px; }
.site-nav { display: flex; align-items: center; gap: 18px; color: rgba(255,255,255,.82); }
.site-nav a { font-size: 14px; }
.nav-cta {
  padding: 11px 16px; border-radius: 999px; background: var(--brand-2); color: #fff; font-weight: 700;
}

.hero { padding: 56px 0 34px; color: #fff; }
.hero-grid {
  display: grid; grid-template-columns: 1.05fr .95fr; gap: 22px; align-items: center;
}
.hero-copy { max-width: 700px; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px; margin: 0 0 14px; padding: 7px 14px;
  border-radius: 999px; background: rgba(255,255,255,.08); color: rgba(255,255,255,.82); font-size: 13px;
}
h1 {
  margin: 0; font-size: clamp(34px, 4vw, 55px); line-height: 1.08; letter-spacing: -0.03em;
  word-break: keep-all; overflow-wrap: normal; max-width: 14em;
}
.hero-lead { margin: 16px 0 0; max-width: 680px; color: rgba(255,255,255,.8); font-size: 18px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 24px; }
.btn {
  display: inline-flex; align-items: center; justify-content: center; min-height: 48px; padding: 0 20px;
  border-radius: 999px; font-weight: 700; border: 1px solid transparent;
}
.btn-primary { background: #fff; color: #12202d; }
.btn-secondary { color: #fff; border-color: rgba(255,255,255,.16); background: rgba(255,255,255,.05); }

.hero-status {
  display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px;
}
.status-chip {
  padding: 14px 16px; border-radius: 18px; font-size: 14px; font-weight: 700; text-align: center;
  background: rgba(255,255,255,.08); border: 1px solid rgba(255,255,255,.08);
}
.status-chip.error { color: #ffd9d4; background: rgba(184, 75, 60, .18); }
.status-chip.warn { color: #ffe8bf; background: rgba(167, 112, 30, .18); }
.status-chip.info { color: #d7eef7; background: rgba(35, 77, 102, .26); grid-column: 1 / -1; }
.status-board {
  grid-column: 1 / -1; padding: 22px; border-radius: 24px; background: rgba(255,255,255,.08); border: 1px solid rgba(255,255,255,.1);
}
.status-board strong { display: block; font-size: 22px; margin-bottom: 8px; }
.status-board p { margin: 0; color: rgba(255,255,255,.76); }

.section { padding: 72px 0; }
.section-alt { background: var(--surface-alt); }
.section-head { max-width: 760px; margin-bottom: 28px; }
.section-kicker {
  margin: 0 0 10px; color: var(--brand); font-weight: 800; letter-spacing: .08em; text-transform: uppercase; font-size: 12px;
}
.section-head h2 { margin: 0; font-size: clamp(28px, 3vw, 42px); line-height: 1.15; }
.section-head p:last-child { margin: 12px 0 0; color: var(--muted); }

.fault-layout { display: grid; grid-template-columns: 1.1fr .9fr; gap: 22px; align-items: stretch; }
.fault-tree, .fault-visual, .check-card, .repair-strip {
  background: var(--surface); border: 1px solid var(--line); border-radius: 24px; box-shadow: var(--shadow);
}
.fault-tree { padding: 24px; }
.tree-root {
  display: inline-flex; align-items: center; padding: 10px 16px; border-radius: 999px;
  background: rgba(35,77,102,.12); color: var(--brand); font-weight: 800; margin-bottom: 18px;
}
.tree-branches { display: grid; gap: 14px; }
.tree-branch {
  position: relative; padding: 18px 18px 18px 22px; border-radius: 18px; background: #f9fbfc; border: 1px solid rgba(20,26,32,.08);
}
.tree-branch::before {
  content: ""; position: absolute; left: 0; top: 50%; width: 6px; height: 36px; transform: translateY(-50%);
  border-radius: 999px; background: var(--brand);
}
.tree-branch strong { display: block; margin-bottom: 4px; font-size: 18px; }
.tree-branch span { color: var(--muted); }
.fault-visual {
  margin: 0; padding: 18px; display: flex; flex-direction: column; gap: 12px; justify-content: space-between;
  background: linear-gradient(180deg, #fff, #eef2f4);
}
.fault-visual img { border-radius: 18px; }
.fault-visual figcaption { color: var(--muted); font-size: 14px; }

.check-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.check-card { padding: 22px; min-height: 200px; }
.check-card span {
  display: inline-flex; width: 34px; height: 34px; border-radius: 50%; align-items: center; justify-content: center;
  background: var(--brand); color: #fff; font-weight: 800; font-size: 13px;
}
.check-card strong { display: block; margin: 14px 0 8px; font-size: 20px; }
.check-card p { margin: 0; color: var(--muted); }

.repair-strip {
  padding: 24px; display: grid; grid-template-columns: 1.2fr .8fr; gap: 18px; align-items: center;
}
.repair-strip h2 { margin: 0; font-size: clamp(26px, 2.8vw, 36px); line-height: 1.15; }
.repair-strip p { margin: 12px 0 0; color: var(--muted); }
.repair-actions { display: flex; gap: 12px; flex-wrap: wrap; justify-content: flex-end; }

.faq-list { display: grid; gap: 12px; }
.faq-item {
  background: var(--surface); border: 1px solid var(--line); border-radius: 22px; overflow: hidden; box-shadow: var(--shadow);
}
.faq-trigger {
  width: 100%; display: flex; align-items: center; justify-content: space-between; gap: 16px; padding: 18px 22px;
  border: 0; background: transparent; font: inherit; text-align: left; cursor: pointer; color: var(--ink);
}
.faq-icon { width: 18px; height: 18px; position: relative; flex: 0 0 18px; }
.faq-icon::before, .faq-icon::after {
  content: ""; position: absolute; inset: 50% auto auto 50%; transform: translate(-50%, -50%);
  background: var(--brand); border-radius: 999px;
}
.faq-icon::before { width: 18px; height: 2px; }
.faq-icon::after { width: 2px; height: 18px; transition: opacity .2s ease; }
.faq-item[aria-expanded="true"] .faq-icon::after { opacity: 0; }
.faq-panel { padding: 0 22px 18px; color: var(--muted); }

.site-footer {
  padding: 34px 0 42px; background: #0f151c; color: rgba(255,255,255,.88);
  border-top: 1px solid rgba(255,255,255,.08);
}
.footer-grid {
  display: grid; grid-template-columns: 1fr 1fr .9fr; gap: 24px; align-items: start;
}
.footer-logo { width: 132px; height: auto; margin-bottom: 14px; }
.footer-brand p { margin: 0; color: rgba(255,255,255,.68); }
.footer-links { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; }
.footer-links h3 { margin: 0 0 10px; font-size: 16px; }
.footer-links a { display: block; color: rgba(255,255,255,.72); margin-top: 8px; }
.footer-cta {
  display: inline-flex; align-items: center; justify-content: center; min-height: 46px; padding: 0 18px;
  border-radius: 999px; background: #fff; color: #13202a; font-weight: 800;
}
.footer-action p { margin: 12px 0 0; color: rgba(255,255,255,.68); }

@media (max-width: 980px) {
  .site-nav { display: none; position: absolute; left: 16px; right: 16px; top: 74px; flex-direction: column; padding: 16px; border-radius: 22px; background: #121923; border: 1px solid rgba(255,255,255,.08); }
  .site-nav.is-open { display: flex; }
  .menu-toggle { display: inline-flex; flex-direction: column; }
  .hero-grid, .fault-layout, .repair-strip, .footer-grid { grid-template-columns: 1fr; }
  .check-grid { grid-template-columns: 1fr; }
  .repair-actions { justify-content: flex-start; }
}

@media (max-width: 720px) {
  .hero { padding-top: 38px; }
  .hero-status { grid-template-columns: 1fr; }
  .status-chip.info { grid-column: auto; }
  .footer-links { grid-template-columns: 1fr; }
}