Force cloze color to override b/u/i

[AnKingMed]

@abdnh can you review this quickly. It was proposed by some students who found that the bold/underline/italic styling was overriding the cloze styling. I wonder if adding html:not code or something like that before the b, u, i might be simpler?

[abdnh]

I think this solution is OK. :not() can be unintuitive. :not(.cloze) b for example doesn't work while :not(.cloze) > b does for simple cases, but breaks with nested elements (e.g. bold inside italic).