testbed/Textualize__textual/docs/examples/styles/box_sizing.css

Screen {
    background: white;
    color: black;
}
App Static {
    background: blue 20%;
    height: 5;
    margin: 2;
    padding: 1;
    border: wide black;
}
#static1 {       
    box-sizing: border-box;
}
#static2 {        
    box-sizing: content-box;
}