Having used phpBB 3.0.12 for a while and beingt used to using the WhoIs Online page and user details checked via the WhoIs pop-up box. There is a difference between phpBB 3.1 Beta 2 and phpBB 3.0.12. There is no margin/padding left and right of content box, also the font-size used looks huge compared to the font-size used with same proSilver theme and phpBB 3.0.12 for this box. Too large a font-size really considering how much information is displayed in that small whois pop-up box.
Compare it to the one used in phpBB 3.0.12 using same ProSilver theme, you'll see what I mean, the difference.