Screen {
    background: lightcoral;
}

#left_pane {
    background: red;
    width: 20;
    overflow: scroll scroll;
}

#middle_pane {
    background: green;
    width: 140;
}

#right_pane {
    background: blue;
    width: 30;
}

.box {
    height: 12;
    width: 30;
}