Combine CSS Attribute and Pseudo-Element Selectors?
This looks like a bug, which has finally been reported. If you add a CSS rule for div[title] anywhere in your stylesheet with at least one declaration, your div[title]:after rule will magically apply. For example:
div:after { content: "NO";}div[title] { display: block;}div[title]:after { content: "YES";}See the updated fiddle.
It also seems to have something to do with your second div having or not having certain HTML attributes, as shown in the comments below.