*{
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body{
    width: 100vw;
    height: 100vh;
    background-color: silver;

    display: grid;
    grid-template-columns: 1fr;
    grid-template-rows: auto 1fr;

}

header{
    min-height: 50px;
    background-color: gold;
}
main{
    overflow: hidden;
}

main .content{
    width: 100%;
    height: 100%;
}