CSS and JS requires lots of unique classes and id's in order to target different items. If there aren't enough, then it makes it difficult to only use CSS and JS to modify the html. It's a very simple thing to add extra classes to be able to target with CSS and JS, so it wouldn't be such a major task if one knows where the template files are called at different locations.

For starters a simple class to add would be the controller name to div#content, or even body so everything is covered. Specific classes on span's that have text that might need to be changed. Specific classes on particular buttons in different locations.

Currently for some items very long strings of CSS selectors to target them. It's not the easiest thing when you need to go:
div > table > td > span > a > img.cm-image { }
just to target something simply because there are other cm-image classes that you don't want to target.

Very simple idea that would be just as simple to implement, yet would provide huge benefits by allowing simple CSS selectors.

Simple, right?