:root {
  --ip-red: #e03333;
  --ip-red-dark: #b02323;
  --ip-blue: #1a5fb4;
  --ip-blue-dark: #14488a;
  --ink: #23272f;
  --muted: #5b6472;
  --line: #e2e6ee;
  --bg: #f7f8fa;
  --card: #ffffff;
  --radius: 10px;
  --maxw: 920px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Segoe UI", "Helvetica Neue", Arial, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.65;
}

a { color: var(--ip-blue); }

a:hover { color: var(--ip-blue-dark); }

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--ip-blue);
  color: #fff;
  padding: 8px 14px;
  border-radius: 0 0 6px 0;
  z-index: 50;
}

.skip-link:focus { left: 0; }

.site-header {
  background: linear-gradient(135deg, var(--ip-blue) 0%, var(--ip-blue-dark) 100%);
  color: #fff;
  padding: 0 20px;
}

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

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: #fff;
  text-decoration: none;
  font-weight: 700;
  font-size: 1.05rem;
}

.brand__mark {
  width: 40px;
  height: 40px;
  border-radius: 8px;
  background: #fff;
  display: grid;
  place-items: center;
  flex: 0 0 auto;
}

.brand__mark svg { display: block; }

.brand__sub { display: block; font-weight: 400; font-size: 0.8rem; opacity: 0.85; }

.site-nav {
  max-width: var(--maxw);
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  padding-bottom: 10px;
}

.site-nav a {
  color: #fff;
  text-decoration: none;
  font-size: 0.92rem;
  padding: 6px 12px;
  border-radius: 999px;
  opacity: 0.9;
}

.site-nav a:hover { background: rgba(255, 255, 255, 0.16); opacity: 1; }

.site-nav a.is-active { background: rgba(255, 255, 255, 0.22); opacity: 1; }

.hero {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 48px 20px 40px;
}

.hero h1 { margin: 0 0 10px; font-size: 2rem; line-height: 1.2; }

.hero p { margin: 0; max-width: 640px; opacity: 0.92; font-size: 1.05rem; }

.hero .hero__meta {
  margin-top: 18px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.badge {
  display: inline-block;
  background: rgba(255, 255, 255, 0.16);
  border: 1px solid rgba(255, 255, 255, 0.35);
  color: #fff;
  font-size: 0.8rem;
  border-radius: 999px;
  padding: 4px 12px;
}

main {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 20px;
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px 32px;
  margin: 0 0 24px;
  box-shadow: 0 1px 3px rgba(20, 30, 60, 0.06);
}

.card h1 { margin-top: 0; font-size: 1.6rem; }

.card h2 { font-size: 1.2rem; margin: 28px 0 8px; color: var(--ip-blue-dark); }

.card h3 { font-size: 1.02rem; margin: 22px 0 6px; }

.card p { margin: 8px 0; }

.card ul, .card ol { margin: 8px 0 8px 24px; padding: 0; }

.card li { margin: 4px 0; }

.meta-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  font-size: 0.85rem;
  color: var(--muted);
  border-bottom: 1px solid var(--line);
  padding-bottom: 16px;
  margin-bottom: 18px;
}

.doc-toc { background: var(--bg); border: 1px solid var(--line); border-radius: 8px; padding: 16px 20px; font-size: 0.95rem; }

.doc-toc ul { margin: 6px 0 0 18px; }

.cta-row { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 20px; }

.btn {
  display: inline-block;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
  padding: 10px 20px;
  border-radius: 8px;
  border: 1px solid transparent;
}

.btn--primary { background: var(--ip-red); color: #fff; }

.btn--primary:hover { background: var(--ip-red-dark); color: #fff; }

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

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

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 16px;
  margin-top: 18px;
}

.feature {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 16px 18px;
  background: #fff;
}

.feature h3 { margin: 0 0 6px; font-size: 1rem; color: var(--ip-blue-dark); }

.feature p { margin: 0; font-size: 0.92rem; color: var(--muted); }

.notice {
  border-left: 4px solid var(--ip-red);
  background: #fdf0f0;
  padding: 12px 16px;
  border-radius: 0 8px 8px 0;
  font-size: 0.95rem;
  margin: 16px 0;
}

.site-footer {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 24px 20px 40px;
  color: var(--muted);
  font-size: 0.85rem;
}

.site-footer__inner {
  border-top: 1px solid var(--line);
  padding-top: 18px;
  display: flex;
  flex-wrap: wrap;
  gap: 12px 24px;
  justify-content: space-between;
}

.site-footer a { color: var(--ip-blue); }

@media (max-width: 560px) {
  .site-header__bar { flex-wrap: wrap; }
  .card { padding: 22px 20px; }
  .hero h1 { font-size: 1.6rem; }
}