#cont {
    width: 100%;
    display: block;
    margin-left: 200px;
    margin-right: auto;
    color: #444;
    font-family: sans-serif;
    position: relative
    }
#I1 {
    width: 100%;
    height: 0;
    display: block;
    margin-left: auto;
    margin-right: auto;
    margin-top: 0;
    background-color: #fff
    }