CSS is like quantum mechanics...anyone who says they understand it does not...LOL!
I really can't tell you why your first code didn't work, I just recall when I once added a block to a page with an unordered list in it, and it didn't work as desired, so I looked at the DOM for an element where it did work, such as a post where the LIST BBCode is used, and I saw the "restore" class selector was used, and I added that to my element and it worked.
For me, CSS is a lot of trial and error.