mod_label messes up layout if content width too big

If the content's width of a mod_label (for example an inserted picture) is too high the whole label will expand beyond the border set by the current format/theme, see screenshot. In Topics format this is not that bad, it is "just" being cut off and looks a bit ugly. However, you cannot access the cut off content at all. In other course formats this could be even worse, see screenshot of tiles_format.

I suggest to add overflow-x: auto to the selector .activity-item .contentwithoutlink

This at least does not mess up the whole course layout.