demo.scss

html {
    font-size: 20px;}

body {
    display: grid;
    grid-template-rows: 180px 3fr 1fr;
    min-height: 90vh;
    box-sizing: border-box;
    
    >header, >footer {
        background-color: rgba(60,110,60,0.5);
        display:flex;
        flex-direction: column;
        align-items: stretch;
        padding: 1rem;

        #layoutinfo {
            color: rgb(160,50,160);
            border: 2px rgb(160,50,160) solid;
            max-width: 80vw;
            margin: auto;
        }
    }
}

main {
    border: 2px solid red;
    min-height: 80vh;
    background-color: rgba(180,20,20,0.05);
    transition: all 5s ease;

    >*, article>* {
        border: 2px solid blue;
        margin: 5px;
        padding: 5px;
        background-color: rgba(30, 30,200,0.1);
        transition: all 5s ease;  

    }

    h1 > span {
        background-color: yellow;
        border: 2px solid magenta;
    }


    >nav {
        background-color: rgba(40,40,100,0.3)
    }

    >aside {
        background-color: rgba(100,70,120,0.3)
    }

    >article {

    }
    >footer {
        background-color: rgba(40,40,100,0.3)
    }
}

main.make_flex_column{
    display: flex;
    flex-direction: column;
    align-items: stretch;
}

main.make_flex_reverse{
    display: flex;
    flex-direction: row-reverse;
}

main.make_flex {
    display: flex;
    >* {
    }
}


main.make_grid {
    display: grid;
    grid-template-areas: "nav nav nav"
                             "aside article article"
                             "footer footer footer";
    >nav {
        grid-area: nav;
    }

    >aside {
        grid-area: aside;
    }

    >article {
        grid-area: article;
        display: grid;
        grid-template-columns: 1fr 3fr;
        grid-template-rows: 1fr 3fr;
        >header {
            grid-column: 1/3;
        }
    }
    >footer {
        grid-area: footer;
    }
    > {
        
    }
}

/* Not really relevant for today but I want you to see how I modified content with pure CSS */
/* p.normal:nth-of-type(2)::after { */
/*     content: ' -    Mwahahahahhaha'; */
/*     background-color: purple; */

/* } */


/* put our media queries here */

@media screen and (max-width: 800px) {
    html {
        font-size: 18px;
    }
    main.make_grid {
        grid-template-areas: "nav" "aside" "article" "footer";
        
    }
}

@media screen and (max-width: 500px) {
    html {
        font-size: 16px;
    }
    body {
        grid-template-rows: 140px 3fr 1fr;
    }
    
    main.make_grid {
        grid-template-areas: "nav" "article" "aside" "footer";
        
    }
}