My board started almost a year ago, shoutbox worked on 3 of 4 templates...so I decided to leave that template alone without shoutbox. My users rushed me to enter the shoutbox there too like 4 months ago. At index everything was white, different font, etc... a mess.
I ve been reading this thread hundreds of times trying to figure WTH the problem is. Did the "view source" thing, and unfortunatelly in this particular template (XP2) I could not find the last command that neils advices. So I gave up and left this shoutbox white.
Until today by accident I decided to go inside the ACP to the Styles Administration, Managment, in order to see if I´m able to edit some colors you know...just for fun in my test board. Well, revised all of themsomething catched my attention. In Xp2 template the value for "stylesheet.css" was set like this...templates/phpXp2/phpXp2.css. Instead of being like the other templates values with the template.css flat without the whole extension. I edited leaving only phpXp2.css in the value.
Went back to Board preview and Shoutbox looks wonderfully

A simple thing can make a whole difference, I was ready to shoot myself LOL.