Responsive container adds custom CSS classes on "bounding-box"- and "widget-content"-div
I have a problem with the new flexcontainer feature. When I add a custom CSS class to a flexcontainer it not only adds this class to the "bounding-box"-div element in the DOM but also to the direct child, the "widget-content"-div of the bounding-box. This behaviour raises many problems for me because when I add a width of 50% to that class, the content of the flexcontainer is effectively only 25% (50% of the bounding-box).
I have created a simple example to illustrate the problem. In this example I created a responsive (advanced) mashup with the "Header and Footer"-template. In the mashup I added the custom CSS class "test-custom-css" to the body flexcontainer (see screenshot below).
After the elements got inserted into the DOM the custom class gets added to the "bounding-box"- and "widget-content"-div element (see screenshot below).
On "normal" widgets the custom CSS class only gets added to the bounding-box element.
I think this is a bug or is it working as intended? If it's not a bug, is there a way to overcome this problem without creating a special CSS rule (i.e. .test-custom-css > .test-custom-css) for every custom CSS class used by a flexcontainer?