SVG

<svg>
  <rect     fill="red"   width="100%" height="100%" />
  <circle   fill="red" />
</svg>

  <svg
    width="200" height="200"
  >
    <rect />
    <circle  cx="100" cy="100" r="100" />
  </svg>

  <svg
    width="200" height="200"
    viewBox="0 0 200 200"
  >
    <rect />
    <circle  cx="100" cy="100" r="100" />
  </svg>

<svg
  width="200" height="200"
  viewBox="0 0 100 100"
>
  <rect />
  <circle  cx="100" cy="100" r="100" />
</svg>

<svg
  width="100" height="100"
  viewBox="0 0 100 100"
>
  <rect />
  <circle  cx="100" cy="100" r="100" />
</svg>

Generate Sprite Sheet Programmatically with Node.js Script (coming soon in an Electron app...)