html:before {
  content: "";
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0.9;
  z-index: -2;
  background-image: url("https://www.itl.cat/pngfile/big/205-2050209_medieval-minecraft-castle-wallpaper-collection-minecraft-builds.png");
  background-size: cover;
}

html:after {
  content: "";
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 1;
  z-index: -1;
  background-color: rgba(0, 0, 0, 0.4);
  background-size: cover;
}

li {
  color: #ddd;
}