* { box-sizing: border-box; }
body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif; margin: 0; color: #0f172a; background: #f8fafc; }
a { color: #0ea5e9; text-decoration: none; }
a:hover { text-decoration: underline; }
header { background: #ffffff; border-bottom: 1px solid #e5e7eb; position: sticky; top: 0; z-index: 10; }
header h1 { margin: 0; padding: 16px 0; font-size: 22px; }
header nav { display: flex; gap: 16px; align-items: center; }
header .container { display: flex; justify-content: space-between; align-items: center; }
.container { max-width: 900px; margin: 0 auto; padding: 16px; }
main section { background: #ffffff; border: 1px solid #e5e7eb; border-radius: 12px; padding: 20px; margin: 16px 0; }
h2 { margin-top: 0; }
details { margin: 8px 0; }
footer { text-align: center; color: #64748b; font-size: 14px; margin: 24px 0; }