The transparent background doesn't show making it unreadable on IE8.
Since c. 18 - 34 % of users on different sites I'm responsible for use IE8 this would be unacceptable to me.
But I've got around this by making a quick fix, replacing the transparent background with a solid colour.
Would be preferable if CSS was separate so could be styled as desired.
I appreciate the non-WP instructions as I have a site that is a mixture of both.