* { box-sizing: border-box; }


body {
    margin: 0;

    /* --- */

    font-family: sans-serif;
}

main {
    margin: 1rem
            auto;

    border: 1px
            solid
            hsl( 0, 0%, 8% );
    border-radius: .25rem;

    padding: 1rem;

    min-width: 20rem;
    max-width: 50%;

    /* --- */

    background-color: hsl( 28, 80%, 50% );
    background-image: linear-gradient(
                          180deg,
                          hsl( 0, 0%, 100%, .25 ),
                          hsl( 0, 0%, 0%, 0 ) 40% 40%,
                          hsl( 0, 0%, 0%, .25 )
                      );

    box-shadow: .6rem
                .4rem
                hsl( 28, 80%, 80% );
}

h1 {
    margin-block-start: .4rem;
}

kbd {
    border-width: .15em;
    border-inline-start-width: .6em;
    border-style: solid;
    border-inline-start-style: ridge;
    border-color: hsl( 165, 75%, 60% );
    border-radius: 0 .3rem .3rem 0;

    padding-inline: .25rem;
    padding-block-end: .15rem;

    /* --- */

    color: hsl( 0, 0%, 100% );
    background-color: hsl( 340, 100%, 16% );

    font-family: "Julia Mono",
                 monospace;
}