Ideas for further UI development
Just a note here:
It could be an interesting idea to basically split the App into multiple sections. Having the Main Screen showing the content, swiping from the left edge could open a basic table of contents and options to manipulate the aspects of viewing that certain file / reading preferences in general, while swiping from the right could open a more technical section with options and preferences for caching, connecting, certificates etc. This could enable usage of the app for both inexperienced users and those with more elaborate expectations.
Notifications / queries for input that will probably be necessary could be displayed at the bottom, similar to the Adress bar. I like that particular style because being at the bottom, these controls can easily be faded out without moving the content