div.dom-fx-fullscreen {
    position: fixed;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
    width: 100%;
    height: 100%;
    margin: 0;
    padding: 0;
    background: rgba(0,0,0,.5);
    z-index: 999999;
}

div.dom-fx-fullscreen > .dom-fx-fullscreen-target {
    position: absolute;
    transition: all .2s;
}