One example is that in app.js there is a regex that looks for /* Structure */. In <= 1.3 this comment came after the swatches, but in 1.4 it's no longer in the default theme. So we might have to put that comment in there again. (Actually it are global styles and not structure CSS that follows after that comment, but this is not relevant)
Another thing is that in 1.4 the default theme doesn't start with swatches, but with some global rules. After the swatches there a few more global rules.