While in the middle of typing a question I saw this
which looks kinda weird. Seems the CSS styles aren't updated for all sites?
Well, it does look nice on Meta Stack Overflow though...
Super User still had some leftover styling specialties in its CSS from back in the days; those were biting us here.
Since those extras aren't needed anymore, we could remove them; after the next build, those question links look like any other link in a sidebar box.
This is a new feature to display similar posts based on the title, content and tags of the question you are currently writing. The existing "Related questions" (now named "Questions with similar titles") under the title only looks at the post title, so this new list should be better.
It is possible that the color scheme is not great on all sites, as this is a new addition and the sidebar previously did not contain as many links as it does now. Feel free to leave a comment on the "feedback requested" post that I linked to.