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

Screen {
    background: #212121;
    color: white 80%;
    layout: horizontal;
}

Static {
    padding: 1 2;
}

.panel1 {
    width: 1fr;
    scrollbar-color: green;
    scrollbar-background: #bbb;
    padding: 1 2;        
} 

.panel2 {
    width: 1fr;
    scrollbar-color: yellow;
    scrollbar-background: purple;
    padding: 1 2;
}