SVG
<svg xmlns="http://www.w3.org/2000/svg" viewBox="-11.5 -10.23174 23 20.46348">
  <title>React Logo</title>
  <circle cx="0" cy="0" r="2.05" fill="#61dafb"/>
  <g stroke="#61dafb" stroke-width="1" fill="none">
    <ellipse rx="11" ry="4.2"/>
    <ellipse rx="11" ry="4.2" transform="rotate(60)"/>
    <ellipse rx="11" ry="4.2" transform="rotate(120)"/>
  </g>
</svg>

CSS
div {
  background-image: url("data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%22-11.5%20-10.23174%2023%2020.46348%22%3E%0A%20%20%3Ctitle%3EReact%20Logo%3C%2Ftitle%3E%0A%20%20%3Ccircle%20cx%3D%220%22%20cy%3D%220%22%20r%3D%222.05%22%20fill%3D%22%2361dafb%22%2F%3E%0A%20%20%3Cg%20stroke%3D%22%2361dafb%22%20stroke-width%3D%221%22%20fill%3D%22none%22%3E%0A%20%20%20%20%3Cellipse%20rx%3D%2211%22%20ry%3D%224.2%22%2F%3E%0A%20%20%20%20%3Cellipse%20rx%3D%2211%22%20ry%3D%224.2%22%20transform%3D%22rotate(60)%22%2F%3E%0A%20%20%20%20%3Cellipse%20rx%3D%2211%22%20ry%3D%224.2%22%20transform%3D%22rotate(120)%22%2F%3E%0A%20%20%3C%2Fg%3E%0A%3C%2Fsvg%3E%0A");
}