* { box-sizing: border-box; }
body { font-family: system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
       margin:0; padding:2rem; background:#f5f7fb; color:#111; }
header { text-align:center; margin-bottom:1.5rem; }
h1 { margin:0; font-size:2rem; }
.tagline { color:#666; margin-top:0.2rem; }
.card { background:white; padding:1rem 1.2rem; border-radius:8px;
       max-width:720px; margin:0 auto; box-shadow:0 2px 6px rgba(0,0,0,0.08); }
button { padding:0.5rem 0.8rem; border-radius:6px; border:none; cursor:pointer; }
footer { text-align:center; margin-top:1.5rem; color:#777; }