My suggestion is that it looks a bit "unclean" because the color scheme differs from the rest of the website.
Here is, in my opinion, the scheme that looks good:
Less so this one because it has white text instead of dark:
So I think it would look cleaner with dark text to make it consistent with how it looks elsewhere.
Don't want to make a big deal out of this, I appreciate all your hard work, Pepe! I have no idea how Flarum works, so just wanted to point it out just in case changing the color is a 30 second job.