With some help from Sames, I now have the entire BottomFeeder obeying the user's text size settings - including the menus, which previously ignored them. This makes the whole thing much more consistent.
Update - The html pane scales up and down with changes in text size as well. To get that work, you'll need to grab the updated Twoflower (html) as well as the updated BottomFeeder. Many thanks to Holger Kleinsorgen for making this possible!