Did you try giving it more margin or padding somewhere? At a quick peek you can increase the size of the picture on line 183 but then it simply exceeds its bounds. Admittedly it's not immediately obvious at a glance, haha. Probably only @poire-z knows the ins and outs of this code, and even then it's been a while.
Edit: see
https://github.com/koreader/koreader...ment-406788025