Screen {
    background: white;
    color:black;
}

#box1 {
    width: 10;
    height: 5;
    background: red 40%;
    box-sizing: content-box;
}


#box2 {
    width: 10;
    height: 5;
    padding: 1;
    background:blue 40%;
    box-sizing: content-box;
}

#box3 {
    width: 10;
    height: 5;
    background:green 40%;
    border: heavy;
    box-sizing: content-box;
}