:root {
  --bg: #f5f5f7;
  --bg-elevated: #ffffff;
  --text: #1d1d1f;
  --text-secondary: #6e6e73;
  --border: rgba(0, 0, 0, 0.08);
  --accent: #1d1d1f;
  --accent-soft: rgba(0, 0, 0, 0.04);
  --link: #0066cc;
  --shadow: 0 2px 16px rgba(0, 0, 0, 0.04);
  --radius: 18px;
  --max: 720px;
  --nav-max: 980px;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #000000;
    --bg-elevated: #1c1c1e;
    --text: #f5f5f7;
    --text-secondary: #a1a1a6;
    --border: rgba(255, 255, 255, 0.12);
    --accent: #f5f5f7;
    --accent-soft: rgba(255, 255, 255, 0.06);
    --link: #2997ff;
    --shadow: 0 2px 20px rgba(0, 0, 0, 0.35);
    color-scheme: dark;
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "SF Pro Display",
    "Helvetica Neue", "Segoe UI", "PingFang SC", "Hiragino Sans GB",
    "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.647;
  font-size: 17px;
  letter-spacing: -0.011em;
  min-height: 100vh;
}

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

a:hover {
  text-decoration: underline;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  background: color-mix(in srgb, var(--bg) 78%, transparent);
  border-bottom: 1px solid var(--border);
}

.site-header-inner {
  max-width: var(--nav-max);
  margin: 0 auto;
  padding: 14px 22px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--text);
  font-weight: 600;
  font-size: 17px;
  letter-spacing: -0.02em;
  text-decoration: none;
}

.brand:hover {
  text-decoration: none;
  opacity: 0.75;
}

.brand-mark {
  width: 22px;
  height: 22px;
  border-radius: 6px;
  background: linear-gradient(145deg, #34c759, #248a3d);
  box-shadow: inset 0 0 0 0.5px rgba(255, 255, 255, 0.25);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.nav-links {
  display: none;
  gap: 4px;
}

@media (min-width: 720px) {
  .nav-links {
    display: flex;
  }
}

.nav-link,
.lang-btn {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--text-secondary);
  font: inherit;
  font-size: 13px;
  font-weight: 500;
  padding: 7px 11px;
  border-radius: 980px;
  cursor: pointer;
  text-decoration: none;
}

.nav-link:hover,
.lang-btn:hover {
  background: var(--accent-soft);
  color: var(--text);
  text-decoration: none;
}

.nav-link.is-active {
  color: var(--text);
  background: var(--accent-soft);
}

.lang-switch {
  display: inline-flex;
  padding: 3px;
  border-radius: 980px;
  background: var(--accent-soft);
  border: 1px solid var(--border);
}

.lang-btn.is-active {
  background: var(--bg-elevated);
  color: var(--text);
  box-shadow: var(--shadow);
}

.page {
  max-width: var(--max);
  margin: 0 auto;
  padding: 48px 22px 96px;
}

.hero {
  margin-bottom: 36px;
}

.eyebrow {
  margin: 0 0 10px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-secondary);
}

.hero h1 {
  margin: 0 0 12px;
  font-size: clamp(32px, 8vw, 48px);
  line-height: 1.08;
  letter-spacing: -0.03em;
  font-weight: 700;
}

.updated {
  margin: 0;
  color: var(--text-secondary);
  font-size: 15px;
}

.lead {
  margin: 18px 0 0;
  color: var(--text-secondary);
  font-size: 19px;
  line-height: 1.47;
  letter-spacing: -0.015em;
}

.toc {
  display: grid;
  gap: 8px;
  margin: 0 0 28px;
  padding: 18px 18px 16px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.toc-title {
  margin: 0 0 4px;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
}

.toc a {
  color: var(--text);
  font-size: 15px;
  padding: 4px 0;
}

.sections {
  display: grid;
  gap: 14px;
}

.card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px 22px;
  scroll-margin-top: 84px;
}

.card h2 {
  margin: 0 0 12px;
  font-size: 22px;
  line-height: 1.2;
  letter-spacing: -0.02em;
  font-weight: 650;
}

.card p {
  margin: 0 0 12px;
  color: var(--text-secondary);
}

.card p:last-child {
  margin-bottom: 0;
}

.card ul {
  margin: 0;
  padding: 0 0 0 1.15em;
  color: var(--text-secondary);
}

.card li {
  margin: 0 0 8px;
}

.card li:last-child {
  margin-bottom: 0;
}

.card strong {
  color: var(--text);
  font-weight: 600;
}

.faq {
  display: grid;
  gap: 10px;
}

.faq-item {
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--accent-soft);
  padding: 16px 16px 14px;
}

.faq-item h3 {
  margin: 0 0 8px;
  font-size: 16px;
  letter-spacing: -0.01em;
}

.faq-item p {
  margin: 0;
  font-size: 15px;
}

.contact-box {
  display: grid;
  gap: 10px;
  margin-top: 8px;
}

.contact-row {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 14px 16px;
  border-radius: 14px;
  background: var(--accent-soft);
  border: 1px solid var(--border);
}

.contact-label {
  font-size: 12px;
  font-weight: 600;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.contact-value {
  color: var(--text);
  font-size: 16px;
  font-weight: 500;
  text-decoration: none;
}

.contact-value:hover {
  color: var(--link);
}

.home-grid {
  display: grid;
  gap: 12px;
  margin-top: 28px;
}

.home-card {
  display: block;
  padding: 22px 20px;
  border-radius: var(--radius);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  color: inherit;
  text-decoration: none;
  transition: transform 0.18s ease, box-shadow 0.18s ease;
}

.home-card:hover {
  text-decoration: none;
  transform: translateY(-1px);
  box-shadow: 0 8px 28px rgba(0, 0, 0, 0.08);
}

.home-card h2 {
  margin: 0 0 6px;
  font-size: 20px;
  letter-spacing: -0.02em;
}

.home-card p {
  margin: 0;
  color: var(--text-secondary);
  font-size: 15px;
}

.home-card .meta {
  margin-top: 14px;
  font-size: 13px;
  font-weight: 600;
  color: var(--link);
}

.site-footer {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 22px 48px;
  color: var(--text-secondary);
  font-size: 13px;
}

.site-footer-inner {
  padding-top: 22px;
  border-top: 1px solid var(--border);
  display: flex;
  flex-wrap: wrap;
  gap: 10px 18px;
  justify-content: space-between;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

.footer-links a {
  color: var(--text-secondary);
}

.footer-links a:hover {
  color: var(--text);
}

[data-i18n][hidden],
[data-lang][hidden] {
  display: none !important;
}

@media (min-width: 640px) {
  .page {
    padding-top: 64px;
  }

  .card {
    padding: 28px 28px;
  }

  .home-grid {
    grid-template-columns: 1fr;
  }
}