UX things.

Let me click anywhere to close the popup. Having to target a small button when reading means I have to stretch my thumb to reach it as it can be far from the word I clicked. Don’t make me have to think about the targeting. Eg when reading I never want to think about HOW to turn a page or where I need to swipe.

Make the scroll bar stay visible or at least make it big enough to easily grab!

Not sure why the reflow is causing a horizontal scroll.

Can you retain chapters from the original epub?

Text size options.

Hide the bottom logo and percentage when reading if I want.

Its possible to convert html to epub but it would be better if you handled web pages natively.

This is a really great language app!