Something I had been banging my head about recently… CSS selectors on multiple attributes. No doubt, CSS selectors are powerful. Selecting on ids and classes are a cinch. And in case you didn’t know, you can string multiple classes together in a selection. div#id.class1.class2.class3 Note: You could probably string multiple ids in a selector, but most proper engines will barf at you or simply return nothing. Despite the utility in being able to select multiple elements by their respective ids in one selector, this is poor form.