#sidebar {
    float: right;
    width: 27%;
    min-width: 300px;
}
.content {
    float: left;
    width: 69%;
}

@media only screen and (max-width: 920px) {
    #sidebar {
        float: none;
        width: 100%;
        min-width: 0px;
    }

    .content {
        float: none;
        width: 100%;
        min-width: 0px;
    }
}