:root {
  --ink: #102a43;
  --muted: #60758a;
  --blue: #1976e9;
  --blue-dark: #0c4ea3;
  --cyan: #3dc7d7;
  --surface: #ffffff;
  --page: #f4f8fb;
  --line: #dce7f0;
  --soft-blue: #eaf5ff;
  --max: 1180px;
  color-scheme: light;
  font-family: "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  min-width: 320px;
  margin: 0;
  background: var(--page);
  color: var(--ink);
  line-height: 1.8;
}

a {
  color: var(--blue-dark);
  text-underline-offset: 4px;
}

.skip-link {
  position: fixed;
  z-index: 20;
  top: 12px;
  left: 12px;
  padding: 10px 16px;
  border-radius: 10px;
  background: var(--ink);
  color: #fff;
  transform: translateY(-150%);
}

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

.content-header {
  position: sticky;
  z-index: 10;
  top: 0;
  border-bottom: 1px solid rgba(16, 42, 67, 0.08);
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(18px);
}

.content-header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: min(calc(100% - 48px), var(--max));
  min-height: 74px;
  margin: 0 auto;
}

.content-brand {
  display: inline-flex;
  align-items: baseline;
  gap: 10px;
  color: var(--ink);
  font-size: 21px;
  font-weight: 780;
  letter-spacing: -0.03em;
  text-decoration: none;
}

.content-brand small {
  color: var(--muted);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.16em;
}

.content-header nav,
.content-footer nav {
  display: flex;
  align-items: center;
  gap: 24px;
}

.content-header nav a,
.content-footer nav a {
  color: var(--muted);
  font-size: 13px;
  text-decoration: none;
  transition: color 160ms ease;
}

.content-header nav a:hover,
.content-header nav a:focus-visible,
.content-footer nav a:hover,
.content-footer nav a:focus-visible {
  color: var(--blue);
}

.content-page {
  width: min(calc(100% - 48px), var(--max));
  margin: 0 auto;
  padding: 64px 0 88px;
}

.content-hero {
  position: relative;
  overflow: hidden;
  margin-bottom: 36px;
  padding: clamp(40px, 6vw, 72px);
  border: 1px solid rgba(25, 118, 233, 0.14);
  border-radius: 28px;
  background:
    radial-gradient(circle at 84% 18%, rgba(61, 199, 215, 0.22), transparent 28%),
    linear-gradient(135deg, #ffffff 0%, #edf7ff 62%, #f5fbff 100%);
  box-shadow: 0 24px 70px rgba(28, 73, 116, 0.08);
}

.content-eyebrow {
  margin: 0 0 14px;
  color: var(--blue);
  font-size: 13px;
  font-weight: 760;
  letter-spacing: 0.14em;
}

.content-hero h1 {
  max-width: 820px;
  margin: 0;
  font-size: clamp(32px, 3.3vw, 40px);
  line-height: 1.15;
  letter-spacing: -0.045em;
}

.content-lead {
  max-width: 780px;
  margin: 22px 0 0;
  color: var(--muted);
  font-size: clamp(16px, 1.6vw, 18px);
}

.content-date {
  display: inline-flex;
  margin-top: 26px;
  padding: 7px 12px;
  border: 1px solid rgba(25, 118, 233, 0.16);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.78);
  color: var(--muted);
  font-size: 12px;
}

.content-layout {
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  align-items: start;
  gap: 28px;
}

.content-toc {
  position: sticky;
  top: 98px;
  display: grid;
  gap: 6px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.82);
}

.content-toc strong {
  margin: 0 10px 6px;
  font-size: 12px;
}

.content-toc a {
  padding: 7px 10px;
  border-radius: 9px;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.45;
  text-decoration: none;
}

.content-toc a:hover,
.content-toc a:focus-visible {
  background: var(--soft-blue);
  color: var(--blue-dark);
}

.content-article {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 24px;
  background: var(--surface);
  box-shadow: 0 18px 54px rgba(28, 73, 116, 0.06);
  font-size: 16px;
  line-height: 1.8;
}

.content-stack-section {
  margin-top: 28px;
}

.content-section {
  padding: 40px clamp(28px, 5vw, 58px);
  scroll-margin-top: 100px;
}

.content-section + .content-section {
  border-top: 1px solid var(--line);
}

.content-section h2 {
  margin: 0 0 16px;
  font-size: clamp(20px, 1.6vw, 22px);
  line-height: 1.35;
  letter-spacing: -0.025em;
}

.content-section h3 {
  margin: 28px 0 8px;
  font-size: 16px;
  line-height: 1.45;
}

.content-section p,
.content-section li {
  color: #425d73;
}

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

.content-section ul,
.content-section ol {
  margin: 14px 0 0;
  padding-left: 1.4em;
}

.content-section li + li {
  margin-top: 8px;
}

.content-note {
  margin-top: 22px;
  padding: 18px 20px;
  border-left: 4px solid var(--cyan);
  border-radius: 0 14px 14px 0;
  background: #eefafa;
  color: #31576a;
}

.help-card-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 20px;
  margin-top: 24px;
}

.help-card {
  display: flex;
  min-height: 210px;
  flex-direction: column;
  justify-content: space-between;
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: 20px;
  background: linear-gradient(145deg, #fff, #f4faff);
  color: inherit;
  text-decoration: none;
  transition: transform 180ms ease, border-color 180ms ease, box-shadow 180ms ease;
}

.help-card:hover,
.help-card:focus-visible {
  border-color: rgba(25, 118, 233, 0.36);
  box-shadow: 0 18px 38px rgba(25, 118, 233, 0.1);
  transform: translateY(-3px);
}

.help-card span {
  color: var(--blue);
  font-size: 12px;
  font-weight: 760;
}

.help-card h2 {
  margin: 12px 0 8px;
  font-size: 18px;
  line-height: 1.35;
}

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

.help-card strong {
  margin-top: 24px;
  color: var(--blue-dark);
  font-size: 13px;
}

.faq-list {
  display: grid;
  gap: 12px;
  margin-top: 20px;
}

.faq-list details {
  padding: 0 20px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: #fbfdff;
}

.faq-list summary {
  padding: 17px 0;
  cursor: pointer;
  font-size: 14px;
  font-weight: 700;
}

.faq-list details p {
  margin: 0;
  padding: 0 0 18px;
}

.content-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 24px;
}

.content-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 20px;
  border-radius: 999px;
  background: var(--blue);
  color: #fff;
  font-size: 13px;
  font-weight: 700;
  text-decoration: none;
}

.content-button--secondary {
  border: 1px solid var(--line);
  background: #fff;
  color: var(--ink);
}

.content-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  width: min(calc(100% - 48px), var(--max));
  margin: 0 auto;
  padding: 28px 0 42px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 12px;
}

:focus-visible {
  outline: 3px solid var(--cyan);
  outline-offset: 4px;
}

@media (max-width: 900px) {
  .content-layout {
    grid-template-columns: 1fr;
  }

  .content-toc {
    position: static;
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .content-toc strong {
    grid-column: 1 / -1;
  }
}

@media (max-width: 760px) {
  .content-header-inner,
  .content-page,
  .content-footer {
    width: min(calc(100% - 32px), var(--max));
  }

  .content-header nav a:first-child,
  .content-brand small {
    display: none;
  }

  .content-page {
    padding: 30px 0 56px;
  }

  .content-hero {
    margin-bottom: 20px;
    padding: 34px 24px;
    border-radius: 22px;
  }

  .content-hero h1 {
    font-size: clamp(28px, 8.2vw, 34px);
  }

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

  .content-section {
    padding: 30px 22px;
  }

  .content-article {
    font-size: 15px;
    line-height: 1.75;
  }

  .content-section h2 {
    font-size: 18px;
  }

  .content-section h3 {
    font-size: 16px;
  }

  .help-card-grid {
    grid-template-columns: 1fr;
  }

  .content-footer {
    align-items: flex-start;
    flex-direction: column;
  }

  .content-footer nav {
    flex-wrap: wrap;
    gap: 12px 20px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition: none !important;
  }
}