* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  background: radial-gradient(circle at center, #0f1a2f 0%, #060b14 70%);
  color: #fff;
  font-family: Arial, sans-serif;
}
.layout {
  padding: 12px;
  text-align: center;
}
canvas {
  max-width: 95vw;
  max-height: 85vh;
  border: 1px solid rgba(255,255,255,0.15);
  background: #02040a;
}