body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;

  /* specific retro wallpaper tile is set randomly by JS onload */
  background-repeat: repeat;
  background-attachment: fixed;
  background-position: center; 
}
canvas {
  display: block;
  margin: auto;
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;

  /* fix fuzziness: https://stackoverflow.com/a/13492784 */
  image-rendering: optimizeSpeed;
  image-rendering: -moz-crisp-edges;
  image-rendering: -o-crisp-edges;
  image-rendering: -webkit-optimize-contrast;
  image-rendering: crisp-edges;
  image-rendering: pixelated;
  -ms-interpolation-mode: nearest-neighbor;
}
a.github {
  position: fixed;
  right: 16px;
  bottom: 16px;
  width: 32px;
  height: 32px;
  text-decoration: none;

  /* lazy CSS trick to make octocat visible on different tiles */
  fill: #fff;
  mix-blend-mode: exclusion;
}