iframe {
    overflow: hidden;
}
.document {
    max-width: 800px;
    margin: .5em auto;
    padding-left: 190px;
    padding-right: 10px;
    overflow: hidden;
}
#sidebar { position: fixed; }
iframe { border: none; }
#sidebar, iframe {
    top: 0;
    left: 0;
    width: 180px;
    height: 100%;
}
@media (max-width: 780px) {
    .document {
        margin: 5px 10px 1em 10px;
        padding: 0;
    }
    #sidebar { position: inherit; }
    #sidebar, iframe {
        width: 100%;
        height: 7em;
    }
}