textual/docs/examples/guide/layout/layers.css

Screen {
    align: center middle;
    layers: below above;
}

Static {
    width: 28;
    height: 8;
    color: auto;
    content-align: center middle;
}

#box1 {
    background: darkcyan;
    layer: above;
}

#box2 {
    layer: below;
    background: orange;
    offset: 12 6;
}