Thanks for the quick response and update.
What made our current setup useful was that all the information was displayed without any drill-down or drop-down, and minimal tap. Only one tap to go from home to textbook page with online and offline options (second tap if not direct link to textbook). While the enlarge text button was a visual annoyance, it was manageable by forum suggestion to change position to top left corner. The enlarge text button was not useful on desktops and marginally on smartphone. Would prefer an option to disable.
I would agree that increasing the width of the text body is useful in filling the screen real-estate, in particular smartphone displays. Left/Right arrows could be less distracting if configurable to appear at top or lower 1/4 of page.
We look forward to the progress on future PB developments.