[Jellby]

I include a commented-out SVG cover in most of my books:

<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"
  width="100%" height="100%" viewBox="0 0 600 800" preserveAspectRatio="xMidYMid meet">
  <rect width="100%" height="100%" fill="rgb(6%,7%,32%)" />
  <rect width="100%" height="200" fill="rgb(0,0,0)" />
  <rect x="100%" y="200" width="200" height="100%" transform="translate(-200,0)" fill="rgb(0,0,0)" />
  <rect x="100%" y="0" width="200" height="200" transform="translate(-200,0)" fill="rgb(6%,7%,32%)" />
  <g fill="rgb(100%,100%,100%)" transform="translate(-230,0)">
    <text x="100%" y="50" text-anchor="end"
      font-size="25" font-weight="bold" font-style="italic">Rudyard Kipling</text>
    <text x="100%" y="130" text-anchor="end" font-size="24" font-weight="bold">
      <tspan x="100%" dy="0">The Jungle Book</tspan>
    </text>
    <text x="100%" y="300" text-anchor="middle" transform="translate(130,0)"
      font-size="20">1894</text>
  </g>
  <image x="50" y="220" height="500" width="300" xlink:href="images/Cover.jpg" />
  <image x="100%" y="0%" height="180" width="180" transform="translate(-190,10)"
    xlink:href="images/Kipling.jpg" />
  <image x="100%" y="100%" height="100" width="100" transform="translate(-150,-120)"
    xlink:href="images/epub.png" />
</svg>

It's not "pure" SVG, because it includes some images, but it's not just an SVG wrapper either.