:root {
  --ink: #18181b;
  --ink-light: #71717a;
  --bg: #ffffff;
  --bg-soft: #fafafa;
  --border: #e4e4e7;
  --accent: #ff5a1f;
  --accent-ink: #ffffff;
  --maxw: 720px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

/* 导航 */
.nav {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 24px;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
}

.brand {
  font-weight: 800;
  font-size: 20px;
  letter-spacing: -0.02em;
}

.brand-dot {
  color: var(--accent);
}

.nav-links {
  display: flex;
  gap: 22px;
  font-size: 15px;
  color: var(--ink-light);
}

.nav-links a:hover {
  color: var(--ink);
}

/* Hero */
.hero {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 96px 24px 72px;
  text-align: center;
}

.eyebrow {
  font-size: 13px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-light);
  margin: 0 0 20px;
}

.hero-title {
  font-size: clamp(56px, 12vw, 104px);
  font-weight: 800;
  letter-spacing: -0.04em;
  margin: 0;
  line-height: 1;
}

.hero-sub {
  font-size: clamp(18px, 3vw, 22px);
  color: var(--accent);
  font-weight: 600;
  margin: 20px 0 28px;
}

.hero-lead {
  font-size: 17px;
  color: var(--ink-light);
  margin: 0 auto 36px;
  max-width: 560px;
}

.hero-actions {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
}

/* 按钮 */
.btn {
  display: inline-block;
  padding: 12px 22px;
  border-radius: 10px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  border: 1px solid transparent;
  transition: transform 0.08s ease, opacity 0.15s ease;
}

.btn:active {
  transform: translateY(1px);
}

.btn-primary {
  background: var(--accent);
  color: var(--accent-ink);
}

.btn-primary:hover {
  opacity: 0.9;
}

.btn-ghost {
  background: transparent;
  color: var(--ink);
  border-color: var(--border);
}

.btn-ghost:hover {
  border-color: var(--ink);
}

/* 区块 */
.section {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 56px 24px;
  border-top: 1px solid var(--border);
}

.section-title {
  font-size: 22px;
  font-weight: 700;
  margin: 0 0 16px;
}

.section-body {
  font-size: 16px;
  color: var(--ink-light);
  margin: 0;
}

/* FAQ */
.faq {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.faq-item {
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 4px 18px;
  background: var(--bg-soft);
}

.faq-item summary {
  cursor: pointer;
  font-weight: 600;
  padding: 14px 0;
  list-style: none;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "+";
  float: right;
  color: var(--ink-light);
  font-weight: 400;
}

.faq-item[open] summary::after {
  content: "−";
}

.faq-item p {
  margin: 0 0 16px;
  color: var(--ink-light);
  font-size: 15px;
}

/* 站点数据 */
.stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  margin-top: 24px;
}

.stat-card {
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--bg-soft);
  padding: 26px 20px;
  text-align: center;
}

.stat-value {
  font-size: clamp(32px, 6vw, 44px);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.1;
  color: var(--accent);
  font-variant-numeric: tabular-nums;
}

.stat-label {
  margin-top: 8px;
  font-size: 14px;
  color: var(--ink-light);
}

.stat-note {
  margin: 14px 0 0;
  font-size: 13px;
  color: var(--ink-light);
}

/* 页脚 */
.footer {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 40px 24px 64px;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  font-size: 13px;
  color: var(--ink-light);
  flex-wrap: wrap;
  gap: 8px;
}

.footer-muted {
  color: var(--border);
}

@media (max-width: 520px) {
  .nav-links {
    gap: 14px;
    font-size: 14px;
  }
  .hero {
    padding-top: 64px;
  }
  .stats {
    grid-template-columns: 1fr;
  }
}