body{font-family:Arial,sans-serif;background:#f3f6fb;margin:0;padding:20px}
.container{max-width:800px;margin:auto;background:#fff;padding:20px;border-radius:16px;box-shadow:0 4px 20px rgba(0,0,0,.1);text-align:center}
h1{margin:0;color:#114488}
.controls button,.download{padding:10px 16px;margin:5px;cursor:pointer}
canvas{max-width:100%;border:1px solid #ccc;margin-top:15px}