JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
        <header><h1>A</h1></header>
        <nav><h1>B</h1></nav>
        <main><h1>C</h1></main>
        <footer><h1>D</h1></footer>
    </div>

CSS

.container {
        display: grid;
        width: 100%;
        height: 100%;
/*     grid-template-areas: "a a"
                         "b c"
                         "d d";
    grid-template-columns: 250px 1fr;
    grid-template-rows: 1fr 70% 1r; */
    
    grid-template-areas: "a b c d"
                         "b c d a"
                         "a b c d";
    grid-template-columns: 1fr 1fr 1fr 1fr;
    grid-template-rows: 1fr 1fr 1fr;
    }

    .container > * {
      border: 1px solid #000;
    }

    .container > header {
        grid-area: a;
    }

    .container > nav {
        grid-area: b;
    }

    .container > main {
        grid-area: c;
    }

    .container > footer {
        grid-area: d;
    }