:root {
  color-scheme: light;
  --bg: #f7f8fb;
  --surface: #ffffff;
  --surface-muted: #eef3f8;
  --text: #17202a;
  --text-muted: #5d6b7a;
  --line: #dce4ec;
  --primary: #0f6f68;
  --primary-strong: #0a4f4a;
  --accent: #d86135;
  --shadow: 0 18px 50px rgba(24, 43, 66, 0.12);
  --radius: 8px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.75;
  letter-spacing: 0;
  text-rendering: optimizeLegibility;
}

a {
  color: var(--primary);
  text-underline-offset: 0.18em;
}

a:hover {
  color: var(--primary-strong);
}

a:focus-visible {
  outline: 3px solid rgba(15, 111, 104, 0.35);
  outline-offset: 4px;
  border-radius: 4px;
}

.skip-link {
  position: absolute;
  left: 16px;
  top: 12px;
  z-index: 10;
  transform: translateY(-140%);
  background: var(--text);
  color: #fff;
  padding: 10px 14px;
  border-radius: 6px;
  text-decoration: none;
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  background: rgba(247, 248, 251, 0.9);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(16px);
  position: sticky;
  top: 0;
  z-index: 5;
}

.nav {
  width: min(1120px, calc(100% - 32px));
  min-height: 64px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.brand {
  color: var(--text);
  font-size: 20px;
  font-weight: 750;
  text-decoration: none;
}

.nav-link {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  color: var(--text);
  font-weight: 600;
  text-decoration: none;
}

.language-menu {
  position: relative;
  z-index: 8;
}

.language-menu summary {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 0 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.86);
  box-shadow: 0 8px 24px rgba(24, 43, 66, 0.08);
  color: var(--text);
  cursor: pointer;
  list-style: none;
  user-select: none;
}

.language-menu summary::-webkit-details-marker {
  display: none;
}

.language-menu summary::after {
  content: "";
  width: 7px;
  height: 7px;
  border-right: 2px solid var(--text-muted);
  border-bottom: 2px solid var(--text-muted);
  transform: translateY(-2px) rotate(45deg);
  transition: transform 160ms ease;
}

.language-menu[open] summary::after {
  transform: translateY(2px) rotate(225deg);
}

.language-label {
  color: var(--text-muted);
  font-size: 13px;
  font-weight: 650;
}

.language-current {
  color: var(--text);
  font-size: 14px;
  font-weight: 750;
}

.language-options {
  position: absolute;
  right: 0;
  top: calc(100% + 8px);
  width: 190px;
  padding: 6px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fff;
  box-shadow: 0 18px 48px rgba(24, 43, 66, 0.16);
}

.language-options a {
  min-height: 40px;
  display: flex;
  align-items: center;
  padding: 8px 10px;
  border-radius: 6px;
  color: var(--text);
  font-size: 14px;
  font-weight: 650;
  line-height: 1.25;
  text-decoration: none;
}

.language-options a:hover {
  background: rgba(15, 111, 104, 0.08);
  color: var(--primary-strong);
}

.language-options a[aria-current="page"] {
  background: var(--primary);
  color: #fff;
}

.hero {
  background:
    linear-gradient(135deg, rgba(15, 111, 104, 0.14), transparent 36%),
    linear-gradient(160deg, #ffffff 0%, #f0f5f4 52%, #f7f8fb 100%);
  border-bottom: 1px solid var(--line);
}

.hero-inner {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
  padding: 72px 0 48px;
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--accent);
  font-size: 13px;
  font-weight: 750;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 18px;
  font-size: clamp(38px, 8vw, 72px);
  line-height: 1.05;
  font-weight: 800;
}

.hero-copy {
  max-width: 720px;
  margin-bottom: 28px;
  color: var(--text-muted);
  font-size: 19px;
  line-height: 1.65;
}

.meta-list {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  max-width: 900px;
  margin: 0;
}

.meta-list div {
  min-width: 0;
  background: rgba(255, 255, 255, 0.78);
  border: 1px solid rgba(220, 228, 236, 0.9);
  border-radius: var(--radius);
  padding: 16px;
}

.meta-list dt {
  color: var(--text-muted);
  font-size: 13px;
  font-weight: 650;
}

.meta-list dd {
  margin: 4px 0 0;
  font-weight: 700;
  overflow-wrap: anywhere;
}

.content-wrap {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
  padding: 44px 0 72px;
  display: grid;
  grid-template-columns: 260px minmax(0, 1fr);
  gap: 36px;
  align-items: start;
}

.toc {
  position: sticky;
  top: 88px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: 0 10px 32px rgba(24, 43, 66, 0.08);
  padding: 18px;
}

.toc h2 {
  margin-bottom: 10px;
  font-size: 16px;
  line-height: 1.4;
}

.toc ol {
  margin: 0;
  padding-left: 20px;
}

.toc li + li {
  margin-top: 6px;
}

.toc a {
  color: var(--text-muted);
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
}

.toc a:hover {
  color: var(--primary);
}

.policy {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 40px;
}

.policy section {
  scroll-margin-top: 96px;
}

.policy section + section {
  margin-top: 40px;
  padding-top: 34px;
  border-top: 1px solid var(--line);
}

.policy h2 {
  margin-bottom: 14px;
  font-size: 25px;
  line-height: 1.35;
}

.policy p {
  color: var(--text-muted);
}

.policy p:last-child,
.policy ul:last-child {
  margin-bottom: 0;
}

.policy ul {
  margin: 0 0 20px;
  padding-left: 22px;
  color: var(--text-muted);
}

.policy li + li {
  margin-top: 10px;
}

.policy strong {
  color: var(--text);
  font-weight: 700;
}

address {
  color: var(--text-muted);
  font-style: normal;
}

.site-footer {
  border-top: 1px solid var(--line);
  background: var(--surface);
  padding: 24px 16px;
  text-align: center;
}

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

@media (max-width: 860px) {
  .hero-inner {
    padding: 56px 0 36px;
  }

  .meta-list {
    grid-template-columns: 1fr;
  }

  .content-wrap {
    grid-template-columns: 1fr;
    gap: 20px;
    padding-top: 24px;
  }

  .toc {
    position: static;
  }

  .toc ol {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 8px 18px;
  }

  .toc li + li {
    margin-top: 0;
  }
}

@media (max-width: 560px) {
  .nav,
  .hero-inner,
  .content-wrap {
    width: min(100% - 24px, 1120px);
  }

  .nav {
    min-height: 58px;
    align-items: flex-start;
    flex-direction: column;
    justify-content: center;
    padding: 10px 0;
  }

  .language-menu {
    width: 100%;
  }

  .language-menu summary {
    width: 100%;
    justify-content: space-between;
  }

  .language-options {
    left: 0;
    right: auto;
    width: min(100%, 260px);
  }

  .hero-inner {
    padding: 42px 0 28px;
  }

  h1 {
    font-size: 40px;
  }

  .hero-copy {
    font-size: 17px;
  }

  .toc {
    padding: 16px;
  }

  .toc ol {
    grid-template-columns: 1fr;
  }

  .policy {
    padding: 24px 18px;
  }

  .policy h2 {
    font-size: 22px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}