*{box-sizing:border-box}
body{margin:0;font-family:Arial,sans-serif;background:#f6f6f6;color:#222}
header{background:#111;color:#fff;text-align:center;padding:28px 15px}
header h1{margin:0;font-size:36px}
.intro{text-align:center;padding:30px 15px}
.catalogo{max-width:1100px;margin:auto;padding:15px;display:grid;grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:18px}
.producto{background:#fff;border-radius:14px;padding:15px;box-shadow:0 2px 12px #0002}
.producto h3{margin-top:0}
footer{text-align:center;padding:30px}
footer a{font-weight:bold}