#content {
    width:100%;
    overflow:hidden;
    background-color:transparent;
    padding:0;
    margin:0;
    border:0;
    }

.contentbox-wrapper{
    width:300%; /* 3 times larger than #content width */
    height:100%;
    transition: transform .500s linear;
    }

.contentbox {
    width:31.3%; /* third of content-wrapper (300% = 100%) */
    height:100%;
    padding:0 1%;
    float:left;
  }