OK, right now the ‘red background’ isn’t working but I know what you mean.
It’s easy to get obsessive with this kind of stuff but you have to remember that you are targeting devices rather than specific widths. Sure, the labels are hard to read at a width of 500px – 600 px but, in real life, no-one is going to be looking at it at that resolution.
However, to answer your query even more specifically, I wouldn’t use images there that include the text. I would use the image of the ‘banners’ as the background of the heading and size the actual text in a media query.
My opinion of course.
Oh, you might want to look at the min-heights of the modules as they sometimes aren’t always the same.