    {% highlight 'css' %}
    .relative { position: relative }
    .absolute { position: absolute }
    .fixed    { position: fixed }

    .top-0    { top: 0 }
    .right-0  { right: 0 }
    .bottom-0 { bottom: 0 }
    .left-0   { left: 0 }

    .z1 { z-index: 1 }
    .z2 { z-index: 2 }
    .z3 { z-index: 3 }
    .z4 { z-index: 4 }

    .absolute-center {
      top: 0;
      right: 0;
      bottom: 0;
      left: 0;
      margin: auto;
      display: table;
    }
    {% endhighlight %}