:root {
  --bg: #f7fafc;
  --paper: #ffffff;
  --text: #172033;
  --muted: #5b667a;
  --line: #dfe7ef;
  --brand: #1677d2;
  --brand-dark: #0f5ea8;
  --green: #0f9f6e;
  --soft: #edf6ff;
  --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", "Microsoft YaHei", Arial, sans-serif;
  font-size: 17px;
  line-height: 1.75;
  padding-bottom: 88px;
}

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

a:hover {
  text-decoration: underline;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, 0.96);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(10px);
}

.nav {
  max-width: 1180px;
  margin: 0 auto;
  padding: 12px 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
}

.brand {
  color: var(--text);
  font-weight: 800;
  white-space: nowrap;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 14px;
  font-size: 15px;
}

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

.support-label {
  color: var(--muted);
  font-size: 14px;
  white-space: nowrap;
}

.menu-toggle {
  display: none;
  min-height: 44px;
  border: 1px solid var(--line);
  background: var(--paper);
  border-radius: var(--radius);
  padding: 0 12px;
  font-size: 16px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 10px 16px;
  border-radius: var(--radius);
  border: 1px solid transparent;
  background: var(--brand);
  color: #fff;
  font-weight: 700;
  line-height: 1.2;
  text-decoration: none;
}

.button:hover {
  background: var(--brand-dark);
  color: #fff;
  text-decoration: none;
}

.button.secondary {
  background: #fff;
  border-color: var(--line);
  color: var(--text);
}

.button.secondary:hover {
  border-color: var(--brand);
  color: var(--brand);
}

.layout {
  max-width: 1180px;
  margin: 0 auto;
  padding: 28px 16px 52px;
  display: grid;
  grid-template-columns: minmax(0, 840px) 280px;
  gap: 32px;
  align-items: start;
}

.content {
  min-width: 0;
}

.hero,
.article,
.section,
.cta,
.card {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.hero {
  padding: 34px;
}

.article,
.section {
  padding: 30px;
  margin-top: 18px;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--green);
  font-weight: 800;
  font-size: 15px;
}

h1,
h2,
h3 {
  line-height: 1.35;
  margin: 0 0 14px;
}

h1 {
  font-size: clamp(30px, 4vw, 44px);
  letter-spacing: 0;
}

h2 {
  margin-top: 6px;
  font-size: 26px;
}

h3 {
  font-size: 20px;
}

p {
  margin: 0 0 14px;
}

ul,
ol {
  padding-left: 1.25em;
  margin: 0 0 14px;
}

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

.lead {
  color: var(--muted);
  font-size: 19px;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 20px;
}

.grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.card {
  padding: 20px;
}

.card h2,
.card h3 {
  font-size: 20px;
}

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

.toc {
  background: var(--soft);
  border: 1px solid #cfe6fb;
  border-radius: var(--radius);
  padding: 18px;
  margin: 18px 0;
}

.toc strong {
  display: block;
  margin-bottom: 8px;
}

.note {
  background: #f3faf6;
  border: 1px solid #ccebdd;
  border-radius: var(--radius);
  padding: 16px;
}

.cta {
  margin-top: 22px;
  padding: 24px;
  border-color: #b7dbf8;
  background: #f2f8ff;
}

.side-contact {
  position: sticky;
  top: 88px;
  padding: 20px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.side-contact strong {
  display: block;
  font-size: 18px;
  line-height: 1.45;
  margin-bottom: 10px;
}

.mobile-contact {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 30;
  display: none;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 10px 14px;
  background: #fff;
  border-top: 1px solid var(--line);
  box-shadow: 0 -8px 24px rgba(23, 32, 51, 0.08);
  font-size: 14px;
}

.site-footer {
  border-top: 1px solid var(--line);
  background: #fff;
  color: var(--muted);
}

.footer-inner {
  max-width: 1180px;
  margin: 0 auto;
  padding: 24px 16px;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 8px;
  font-size: 15px;
}

code {
  background: #eef3f8;
  border-radius: 5px;
  padding: 2px 5px;
}

@media (max-width: 980px) {
  .layout {
    display: block;
  }

  .side-contact {
    display: none;
  }

  .mobile-contact {
    display: flex;
  }
}

@media (max-width: 820px) {
  body {
    font-size: 16px;
  }

  .nav {
    flex-wrap: wrap;
  }

  .menu-toggle {
    display: inline-flex;
    align-items: center;
  }

  .nav-links {
    display: none;
    width: 100%;
    flex-direction: column;
    align-items: stretch;
    padding-top: 10px;
  }

  .nav-links.open {
    display: flex;
  }

  .nav-links a {
    min-height: 44px;
    display: flex;
    align-items: center;
  }

  .support-label {
    display: none;
  }

  .hero,
  .article,
  .section {
    padding: 22px 18px;
  }

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

  h1 {
    font-size: 30px;
  }

  h2 {
    font-size: 23px;
  }
}