I am a user who used to view articles from my mobile. I haven't yet tried to edit wikipedia through it. I have recently opened wikipedia from my mobile phone through Google Chrome browser. I then took the 'view history' page of a random article. I then tried to thank an edit done by a user. In the text that appears ie. 'Publicly send thanks?', I am seeing it in a too low font. I mean the size. So I suggest you to increase the font size for that specific text including the buttons thanks and cancel. All these changes needs to be made only in that confirmation menu.
Topic on Talk:Reading/Web/Projects/Mobile Page Issues/Flow
Just for posterity, I replied on English Wikipedia and created a task for you. :)