body{font-family:Arial;margin:0;background:#f4f4f4;padding:20px}
header,nav{padding:15px;background:#222;color:white;text-align:center}
nav a{color:white;margin:10px;text-decoration:none}
.hero,.box,.card,form{background:white;padding:20px;margin:20px;border-radius:8px}
.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:15px}
.card{box-shadow:0 1px 4px rgba(0,0,0,.2)}