#left {
    dock: left;
    height: 100%;
    width: auto;
    align-vertical: middle;
}
#top {
    dock: top;
    height: auto;
    width: 100%;
    align-horizontal: center;
}
#right {
    dock: right;
    height: 100%;
    width: auto;
    align-vertical: middle;
}
#bottom {
    dock: bottom;
    height: auto;
    width: 100%;
    align-horizontal: center;
}

Screen {
    align: center middle;
}

#big_container {
    width: 75%;
    height: 75%;
    border: round white;
}