Push CSS overrides to the appropriate project

If we need to override a bbPress core style then it will be better to push a change to bbPress to make the CSS selector more specific and less able to interfere with other things.

The issue names no repository file or test; begin by locating the bbPress core style being overridden and confirming which selector interferes with other elements. Identify the appropriate bbPress project and define the required selector-specificity change there; done means the override is no longer needed without causing regressions.

Written by the indexing model from the issue text.