html,body {margin:0; padding:0; position:absolute; width:100%; height:100%; overflow: hidden}
#screen {width:80%; height:50%; background:#ddd; position: absolute; left:10%; top:10%; overflow:hidden}
span.blue, span.green, span.gray, span.red {
    position: absolute;
    font-size: 0;
    -webkit-border-radius: 5px;
    -moz-border-radius: 5px;
    -o-border-radius: 5px;
    border-radius: 5px;
}
.blue {background: #06c}
.green {background: #4eb84a}
.gray {background: #f3f3f3}
.red {background: #da4901}