/* h5: compact bar + industrial fault board */
:root {
  --bg: #f4f4f5;
  --bar: #3f3f46;
  --warn: #d97706;
  --card: #ffffff;
  --ink: #18181b;
  --muted: #52525b;
  --line: #d4d4d8;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: auto;
}

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

a {
  color: #a16207;
}

.topbar {
  background: var(--bar);
  color: #fafafa;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 20px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 8px;
  color: #fafafa;
  text-decoration: none;
  font-weight: 700;
  white-space: nowrap;
}

.nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 6px 14px;
}

.nav a {
  color: #e4e4e7;
  text-decoration: none;
  font-size: 0.82rem;
}

.nav a:hover,
.nav a:focus {
  color: #fde68a;
}

.stage {
  width: min(1100px, calc(100% - 32px));
  margin: 0 auto;
  padding: 24px 0 44px;
}

.hero {
  margin-bottom: 20px;
}

.hero h1 {
  margin: 0 0 12px;
  font-size: 1.9rem;
  color: var(--bar);
}

.hero p {
  margin: 0 0 10px;
  color: var(--muted);
}

.symptoms {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin: 0 0 36px;
}

.sym {
  background: var(--card);
  border-top: 4px solid var(--warn);
  padding: 16px;
  box-shadow: 0 1px 0 #e4e4e7;
}

.sym h3 {
  margin: 8px 0;
  font-size: 1.05rem;
}

.sym p {
  margin: 0;
  color: var(--muted);
}

.sec {
  margin: 0 0 36px;
}

.sec h2 {
  margin: 0 0 10px;
  font-size: 1.4rem;
  color: var(--bar);
}

.sec p {
  margin: 0 0 12px;
}

.layers {
  width: 100%;
  border-collapse: collapse;
  background: var(--card);
}

.layers th,
.layers td {
  border: 1px solid var(--line);
  padding: 10px 12px;
  text-align: left;
  vertical-align: top;
}

.layers th {
  background: #fff7ed;
  color: #92400e;
}

.process {
  display: flex;
  gap: 0;
  background: var(--card);
  border: 1px solid var(--line);
  overflow-x: auto;
}

.proc {
  flex: 1;
  min-width: 160px;
  padding: 14px 12px;
  border-right: 1px solid var(--line);
}

.process .proc:last-child {
  border-right: none;
}

.proc b {
  display: block;
  color: var(--warn);
  margin-bottom: 6px;
}

.pair {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.box {
  background: var(--card);
  padding: 16px;
  border: 1px solid var(--line);
}

.box h3 {
  margin: 8px 0;
}

.three {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}

.warn-list {
  background: #fffbeb;
  border: 1px solid #fcd34d;
  padding: 16px 18px;
}

.warn-list ol {
  margin: 8px 0 0;
  padding-left: 20px;
}

.checkrow {
  background: var(--card);
  border-left: 6px solid var(--warn);
  padding: 16px 18px;
}

.faq-num {
  counter-reset: q;
}

.faq-item {
  background: var(--card);
  border: 1px solid var(--line);
  padding: 14px 16px 14px 64px;
  margin: 0 0 10px;
  position: relative;
}

.faq-item::before {
  counter-increment: q;
  content: counter(q);
  position: absolute;
  left: 14px;
  top: 14px;
  width: 36px;
  height: 36px;
  background: var(--bar);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
}

.faq-item h3 {
  margin: 0 0 8px;
  font-size: 1.02rem;
}

.faq-item p {
  margin: 0;
  color: var(--muted);
}

.foot {
  background: var(--bar);
  color: #e4e4e7;
  padding: 24px 20px;
}

.foot p {
  margin: 0 0 8px;
}

@media (max-width: 860px) {
  .topbar {
    flex-direction: column;
    align-items: flex-start;
  }

  .nav {
    justify-content: flex-start;
  }

  .symptoms,
  .three,
  .pair {
    grid-template-columns: 1fr;
  }
}