:root {
  --bg0: #0d0d0d;
  --bg1: #262626;
  --ink: #f5f5f5;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  min-height: 100%;
  background: radial-gradient(circle at 30% 20%, var(--bg1), var(--bg0) 60%);
  font-family: "Trebuchet MS", Tahoma, sans-serif;
}

body {
  display: grid;
  place-items: center;
  padding: 12px;
}

canvas {
  max-width: min(96vw, 720px);
  height: auto !important;
  border: 2px solid var(--ink);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.45);
}