CSS Transitions

[hbulens]

Is there a clean way to support CSS transitions as shown in this pen? I had to modify the _$maximiseItem function to make this work:

.lm_stack {
  transition: width .5s;
}
    
_$maximiseItem: function (contentItem) {
        if (this._maximisedItem !== null) {
            this._$minimiseItem(this._maximisedItem);
        }
        this._maximisedItem = contentItem;
        this._maximisedItem.addId('__glMaximised');
        contentItem.element.addClass('lm_maximised');
        contentItem.element.after(this._maximisePlaceholder);
        this.root.element.prepend(contentItem.element);

        var me = this;
        contentItem.element.width(this.container.width());
        contentItem.element.height(this.container.height());

        setTimeout(function () {
            contentItem.callDownwards('setSize');                
        }, 500);
}

Of course this is not how it should work but at least it gives a fluent motion when maximizing and minimizing the panes. Any idea on how to call the contentItem.callDownwards('setSize') when the animation is done?