:root{--bg: #e8f0f8;--panel: #f5f8fc}*{box-sizing:border-box}html,body{margin:0;min-height:100%}body{min-height:100vh;display:grid;place-items:center;background:linear-gradient(135deg,#e8f0f8,#d0dbe8);font-family:Trebuchet MS,Segoe UI,sans-serif}#app{width:min(100vw,980px);padding:10px}canvas{width:100%;height:auto;display:block;border:2px solid #b8c8d8;border-radius:12px;background:var(--panel)}