grid-layout-4.css

 @media (max-width: 800px) {
    .container {
        grid-template-columns: minmax(auto, 200px) 1fr;
        grid-template-rows: auto auto 1fr auto;
        grid-template-areas:
        "header   header"
        "nav      nav"
        "side-bar content"
        "footer footer";
    }
}