:root {
    --columns-count: 3;
    --columns-gap: 20px;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    width: 100vw;
    height: 100vh;
    /*padding: 10px;*/
    /*background-color: bisque;*/
}


.container {
    width: 100%;
    height: 100%;
    /*padding: 20px;*/
    /*background-color: brown;*/

    display: grid;
    grid-template-columns: 200px 1fr;
    grid-template-rows: 1fr;
    grid-template-areas: "nav main";
}

aside {
    grid-area: nav;
    background-color: green;
}

main {
    grid-area: main;
    padding: 20px;
    background-color: gray;
    overflow: hidden;
}

article {
    position: relative;
    max-height: 100%;
    columns: var(--columns-count);
    column-gap: var(--columns-gap);
    overflow: hidden;
    
    column-rule: 2px solid black;
}

.content {
    position: relative;
    /*background-color: #ff000030;*/
    /*padding: 10px;*/
}

article img {
    max-height: 100%;
    max-width: 100%;
    margin-left: auto;
    margin-right: auto;
    display: block;
}


@media screen and (max-width: 800px) {
    :root {
        --columns-count: 2;
    }
    .container {
        background-color: red;
    
        grid-template-columns: 1fr;
        grid-template-rows: 30px 1fr;
        grid-template-areas: "nav" "main";
    }
}