style.css

.test {
    height: 200px;
    width: 200px;
    background: purple;
}

#viewport {
    background-image: url('night-sky.jpg');
    bottom: 0;
    left: 0;
    overflow: hidden;
    perspective: 400;
    -webkit-perspective: 400;
    -moz-webkit-perspective: 400;
    -ms-webkit-perspective: 400;
    -o-webkit-perspective: 400;
    position: absolute;
    right: 0;
    top: 0;
    /*background-image: url("skyscraper.jpg");*/
    background-color: rgba(0,0,0,.5);
}

#world {
    height: 512px;
    left: 50%;
    margin-left: -256px;
    margin-top: -256px;
    position: absolute;
    top: 50%;
    transform-style: preserve-3d;
    -webkit-transform-style: preserve-3d;
    width: 512px;
    opacity: ;
}

.cloudBase {
    background: ;
    height: 20px;
    left: 256px;
    margin-left: -10px;
    margin-top: -10px;
    position: absolute;
    top: 256px;
    width: 20px;
    opacity: .4;
    transform-style: preserve-3d;
    -webkit-transform-style: preserve-3d;
}

.cloudLayer {
    background-color: rgba( 0, 0, 0, .01 );
    height: 256px;
    width: 256px;
    left: 50%;
    margin-left: -128px;
    margin-top: -128px;
    position: absolute;
    top: 50%;
    -webkit-transition: opacity .5s ease-out;
    -moz-transition: opacity .5s ease-out;
    -o-transition: opacity .5s ease-out;
}


.moon {
    float: right;
    width: 200px;
    height: 200px;
    background: url(http://maps.jpl.nasa.gov/textures/ear1ccc2.jpg);
    border-radius: 50%;
    background-size: 500px;
    transform-style: preserve-3d;
    box-shadow: inset 16px 0 40px 6px rgb(0, 0, 0),
        inset -3px 0 6px 2px rgba(255, 255, 255, 0.2);
    -webkit-transform: rotate(30deg);
        -webkit-animation-name: rotate;
        -webkit-animation-duration: 15s;
        -webkit-animation-iteration-count: infinite;
        -webkit-animation-timing-function: linear;
}

@-webkit-keyframes rotate {
  from { background-position-x: 500px; }
  to { background-position-x: 0px; }
}
@keyframes rotate {
  from { background-position-x: 500px; }
  to { background-position-x: 0px; }
}