redstrate.com/themes/red/assets/css/site.css

body {
    background-color: #eebebe;

    display: grid;
    grid-template:
        "head head"
        "nav  main"
        "nav  foot";
}

header {
    grid-area: head;
}

aside {
    background-color: #e3e3e3;

    width: 250px;

    grid-area: nav;
}

article {
    background-color: #e3e3e3;
    grid-area: main;
}

footer {
    grid-area: foot;
}