#header {
    border-radius: 5px;
    height: 50px;
    color: silver;
    position: fixed;
    z-index: 1;
}
.left {
    border-radius: 5px;
    height: 500px;
    color: gray;
    float: left;
}
.right {
    border-radius: 5px;
    height: 500px;
    background: white;
    float: right;
}
#footer {
    border-radius: 5px;
    height: 50px;
    background: silver;
    clear: both;