:root {
  --primary: #4f46e5;
  --primary-dark: #3730a3;
  --text: #0f172a;
  --text-muted: #475569;
  --border: #e2e8f0;
  --bg: #ffffff;
  --bg-muted: #f8fafc;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  font-size: 17px;
}
header.topbar {
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  position: sticky;
  top: 0;
  z-index: 10;
}
.topbar-inner {
  max-width: 760px;
  margin: 0 auto;
  padding: 14px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.brand {
  font-weight: 700;
  font-size: 20px;
  color: var(--primary);
  text-decoration: none;
}
.cta {
  background: var(--primary);
  color: white;
  padding: 8px 16px;
  border-radius: 8px;
  text-decoration: none;
  font-weight: 600;
  font-size: 14px;
}
.cta:hover { background: var(--primary-dark); }
main {
  max-width: 760px;
  margin: 0 auto;
  padding: 40px 20px 80px;
}
h1 {
  font-size: 36px;
  line-height: 1.25;
  margin: 0 0 12px;
  font-weight: 800;
}
h2 {
  font-size: 26px;
  margin: 40px 0 12px;
  font-weight: 700;
}
h3 {
  font-size: 20px;
  margin: 28px 0 8px;
  font-weight: 600;
}
.meta {
  color: var(--text-muted);
  font-size: 14px;
  margin-bottom: 32px;
}
p { margin: 0 0 16px; }
ul, ol { margin: 0 0 16px; padding-inline-start: 24px; }
li { margin-bottom: 6px; }
.box {
  background: var(--bg-muted);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 18px 22px;
  margin: 24px 0;
}
.box h3 { margin-top: 0; }
code {
  background: var(--bg-muted);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.92em;
  font-family: 'SF Mono', Consolas, Monaco, monospace;
  direction: ltr;
  display: inline-block;
}
.highlight-cta {
  background: linear-gradient(135deg, #eef2ff 0%, #f5f3ff 100%);
  border: 1px solid #c7d2fe;
  border-radius: 12px;
  padding: 24px;
  margin: 36px 0;
  text-align: center;
}
.highlight-cta h3 {
  margin-top: 0;
  color: var(--primary-dark);
}
.highlight-cta a {
  display: inline-block;
  background: var(--primary);
  color: white;
  padding: 12px 28px;
  border-radius: 8px;
  font-weight: 600;
  text-decoration: none;
  margin-top: 8px;
}
footer {
  border-top: 1px solid var(--border);
  padding: 24px 20px;
  text-align: center;
  color: var(--text-muted);
  font-size: 14px;
}
footer a { color: var(--primary); text-decoration: none; }
.lang-switch {
  margin: 24px 0 8px;
  padding: 12px 16px;
  background: var(--bg-muted);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  color: var(--text-muted);
}
.lang-switch a {
  color: var(--primary);
  text-decoration: none;
  margin: 0 6px;
}
.lang-switch a:hover { text-decoration: underline; }