There is a lot of unnecessary spacing around the checkboxes for the pseudo-classes in the styles sidebar.
Created attachment 312209 [details] Patch
Created attachment 312210 [details] [Image] After Patch is applied
I'm not sure I agree. The extra spacing emphasizes that pseudo-class toggles are not related to the first CSS rule in the sidebar, the inline style rule.
Comment on attachment 312209 [details] Patch r- for now, I think Nikita has a good point. Also, the height of the pseudo class area (31px) is related to the height of the navigation bar above it (29px, the difference is probably borders). Is the new height arbitrary or does it correspond to something? That said I think it would be a good idea to revisit the Styles sidebar in the future, but we should do that as part of a larger effort to streamline the UI.