body { font-family: system-ui, Arial, sans-serif; margin:0; padding:0; background:#f9fafb; }
header { background:white; padding:10px 20px; border-bottom:1px solid #ddd; display:flex; align-items:center; justify-content:space-between; }
nav a { margin:0 10px; text-decoration:none; color:#0ea5e9; font-weight:500; }
nav a:hover { text-decoration:underline; }
main { max-width:800px; margin:20px auto; padding:0 20px; }
footer { text-align:center; padding:20px; font-size:12px; color:#666; }