@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800;900&display=swap');

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  color: #0f172a;
  font-family: 'Inter', -apple-system, system-ui, sans-serif;
  font-size: 16px;
  line-height: 1.65;
  background: #ffffff;
  -webkit-font-smoothing: antialiased;
}
a { color: #0891b2; text-decoration: none; }
a:hover { text-decoration: underline; }

.topbar {
  position: sticky; top: 0; z-index: 10;
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(16px) saturate(180%);
  border-bottom: 1px solid rgba(15,23,42,0.06);
}
.topbar-inner {
  max-width: 860px; margin: 0 auto; padding: 14px 24px;
  display: flex; align-items: center; justify-content: space-between;
}
.brand { display: flex; align-items: center; gap: 10px; }
.brand-mark {
  width: 30px; height: 30px; border-radius: 8px;
  background: linear-gradient(135deg, #0d9488, #0891b2);
  color: #fff; font-weight: 900; font-size: 14px;
  display: grid; place-items: center;
}
.brand-text { font-weight: 800; font-size: 17px; letter-spacing: -0.02em; }
.back-link { font-size: 14px; color: #64748b; font-weight: 500; }
.back-link:hover { color: #0891b2; }

main {
  max-width: 760px; margin: 0 auto; padding: 48px 24px 80px;
}

h1 {
  font-size: 36px; font-weight: 800; letter-spacing: -0.03em;
  margin-bottom: 12px;
}
.subtitle { color: #64748b; font-size: 15px; margin-bottom: 48px; }

h2 {
  font-size: 22px; font-weight: 700; letter-spacing: -0.02em;
  margin: 40px 0 12px;
}
h3 {
  font-size: 17px; font-weight: 700;
  margin: 24px 0 8px; color: #0f172a;
}
p, ul, ol { margin: 0 0 14px; color: #334155; }
ul, ol { padding-left: 22px; }
li { margin-bottom: 6px; }

.lang-switch {
  display: inline-flex; gap: 4px;
  background: #f1f5f9; padding: 4px; border-radius: 10px;
  margin-bottom: 32px; font-size: 13px;
}
.lang-switch a {
  padding: 6px 14px; border-radius: 6px;
  color: #64748b; font-weight: 600;
}
.lang-switch a.active { background: #fff; color: #0f172a; box-shadow: 0 1px 2px rgba(15,23,42,0.06); }

.callout {
  background: linear-gradient(135deg, #f0fdfa, #ecfeff);
  border: 1px solid #99f6e4;
  border-radius: 14px;
  padding: 20px 24px;
  margin: 28px 0;
  font-size: 15px;
}
.callout strong { color: #0f766e; }

.callout.warn {
  background: linear-gradient(135deg, #fef3c7, #fef9c3);
  border-color: #fde68a;
}
.callout.warn strong { color: #b45309; }

table.data {
  width: 100%; border-collapse: collapse; margin: 16px 0 24px;
  font-size: 14px;
}
table.data th, table.data td {
  border: 1px solid #e2e8f0; padding: 10px 14px; text-align: left; vertical-align: top;
}
table.data th { background: #f8fafc; font-weight: 600; color: #0f172a; }

code, .mono { font-family: ui-monospace, 'SF Mono', Consolas, monospace; font-size: 13px; background: #f1f5f9; padding: 2px 6px; border-radius: 4px; color: #0f766e; }

footer {
  max-width: 760px; margin: 48px auto 0; padding: 24px;
  border-top: 1px solid #e2e8f0; font-size: 13px; color: #94a3b8;
  display: flex; flex-wrap: wrap; gap: 16px; justify-content: space-between;
}
footer a { color: #64748b; font-weight: 500; }
footer .footer-nav { display: flex; gap: 16px; flex-wrap: wrap; }

@media (max-width: 640px) {
  h1 { font-size: 28px; }
  main { padding: 32px 20px 60px; }
}