:root {
  --ink: #141210;
  --char: #1c1917;
  --panel: #292524;
  --line: #44403c;
  --orange: #fb923c;
  --orange-dim: #9a3412;
  --cream: #fff7ed;
  --muted: #d6d3d1;
  --text: #f5f5f4;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: auto;
}

body {
  margin: 0;
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--char);
  color: var(--text);
  line-height: 1.7;
}

a {
  color: var(--orange);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.wrap {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
}

.topbar {
  background: #0c0a09;
  border-bottom: 3px solid var(--orange);
}

.topbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 68px;
  padding: 10px 0;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--cream);
  font-weight: 700;
  letter-spacing: 0.02em;
  white-space: nowrap;
}

.brand svg {
  display: block;
  color: var(--orange);
}

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 16px;
  justify-content: flex-end;
}

.nav a {
  color: var(--muted);
  font-size: 14px;
}

.hero {
  padding: 48px 0 28px;
}

.hero h1 {
  margin: 0 0 16px;
  font-size: clamp(28px, 4vw, 40px);
  line-height: 1.25;
  color: var(--cream);
}

.hero p {
  margin: 0 0 10px;
  max-width: 46em;
  color: var(--muted);
}

.bricks {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin: 8px 0 36px;
}

.brick {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 18px 16px 16px;
  border-top: 6px solid var(--orange);
}

.brick strong {
  display: block;
  font-size: 22px;
  color: var(--orange);
  margin-bottom: 8px;
}

.brick p {
  margin: 0;
  font-size: 14px;
  color: var(--muted);
}

.section {
  margin: 0 0 40px;
  padding: 28px 24px;
  background: #211e1c;
  border: 1px solid var(--line);
  border-radius: 4px;
}

.section h2 {
  margin: 0 0 14px;
  font-size: 24px;
  color: var(--cream);
}

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

.battery-wrap {
  margin: 18px 0;
  padding: 16px;
  background: #0c0a09;
  border: 1px solid var(--orange-dim);
}

.battery-meta {
  display: flex;
  justify-content: space-between;
  font-size: 13px;
  color: var(--orange);
  margin-bottom: 8px;
}

.split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 16px;
}

.card h3 {
  margin: 0 0 10px;
  font-size: 17px;
  color: var(--orange);
}

.card p,
.card li {
  color: var(--muted);
}

.reason-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 15px;
}

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

th {
  background: #0c0a09;
  color: var(--orange);
}

td {
  background: var(--panel);
}

.steps {
  display: grid;
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: step;
}

.steps li {
  display: grid;
  grid-template-columns: 36px 1fr;
  gap: 12px;
  padding: 12px;
  background: var(--panel);
  border-left: 4px solid var(--orange);
}

.steps li::before {
  counter-increment: step;
  content: counter(step);
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  background: var(--orange);
  color: #0c0a09;
  font-weight: 700;
}

.note-list {
  margin: 0;
  padding-left: 1.2em;
}

.note-list li {
  margin: 0 0 8px;
}

details {
  border: 1px solid var(--line);
  background: var(--panel);
  margin: 0 0 10px;
  border-radius: 4px;
}

summary {
  cursor: pointer;
  padding: 12px 14px;
  color: var(--cream);
  font-weight: 600;
}

details p {
  margin: 0;
  padding: 0 14px 14px;
  color: var(--muted);
}

.foot {
  background: #0c0a09;
  border-top: 3px solid var(--orange);
  padding: 28px 0 36px;
  color: #a8a29e;
  font-size: 14px;
}

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

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

  .bricks,
  .split,
  .reason-grid {
    grid-template-columns: 1fr;
  }
}