There seem to be some errors in this file:
/wp-content/plugins/bbpress/templates/default/css/bbpress.css

Specifically, lines 1137-1139 get highlighted by CSS debuggers.

I was using a third party tool to generate Critical CSS for mobile optimization. These lines prevented the CSS from being parsed properly. I had to remove them temporarily, run the tool, then add them back afterwards. Perhaps these lines can be fixed/changed in the next version?

[@robkk Moderator 8 years, 3 months ago]

I think its already removed in version 2.6

[@van24 Participant 8 years, 3 months ago]

Got it, thanks!