Drop Down menu

I was looking for any good walkthroughs on how to make drop down menus in wordpress, preferrably all CSS with no Javascript.

Also looking for themese with already built in drop down menus that I could check out and see how they are made.

I’d like for it to automatically drop down child pages when the cursor is over it. Not something where I have to go in and edit every time I want to add a page.

Thanks in advance!