header {
    background-color: blue;
    color: white;
    text-align: center;
    padding: 5px;
}

nav {
    background-color: yellow;
    padding: 7px;
}

section {
    padding: 15px;
    margin: 10px 10px 10px 10px;
    width: 300px;
    float: left;
}

aside {
    background-color: blue;
    color: yellow;
    padding: 15px;
    margin: 10px 0px 10px 350px;
}

footer {
    background-color: red;
    color: white;
    clear: both;
    text-align: center;
    padding: 5px;
}

div#allcontent {
    width: 840px;
    margin-left: auto;
    margin-right: auto;
}