html, body {
    height: 100%;
    background-color: #4B4B4B;
}

iframe {
    border: 0;
    margin: 0;
    width: 100%;
    height: 100%;
}

header {
    display: block;
    float: left;
    width: 100%;
    height: 70px;
}

footer {
    width: 100%;
}

nav {
    display: block;
    float: left;
    left: 0;
    border: 0;
    margin: 0 0 0 -10px;
    width: 20%;
}

article {
    display: block;
    float: left;
    width: 80%;
    height: 80%;
}