.filler { position: absolute; top: 0; left: 0; width: 3900px; height: 100%; }
  #container { width: 3900px; position: absolute; top: 50%; margin-top: -150px; }

.section { 
      display: block; 
      width: 300px; 
      height: 300px; 
      float: left; 
      margin-left: 20px; 
      opacity: .6; 
      border-radius: 6px; 
    }
  .clear { clear: both; }

    .blue { background-color: #06F; }
    .green { background-color: #0f9d00; }
    .red { background-color: #F00; }
    .yellow { background-color: #ffea00; }