Talk about: When shouldn't you use class selectors?

You should be cautious when using global element selectors(like ul{} for example). Its hard to avoid that styling later on (unless you don't use that element..).

Exceptions to this rule that I can think of now is:
- a{}

Since if you use element selectors you should be aware that the styling in that selector should make sense to have on that element everywhere. If it doesn't you will have to undo the styling later on.

Example that I think is done alot (and probably should be avoided?):

ul{
padding: 0 0 0 20px;
}

No file, test, or entry point is named. Read the issue discussion and inspect the repository for existing CSS or style-guide documentation; done means the selector guidance and exceptions are agreed and recorded in the appropriate project documentation.

Written by the indexing model from the issue text.