When the search bar is displayed it hides top right corner of text.
When using a dark background the next/previous page vertical bars flash white when the mouse is moved over them. I would never click on those bars, perhaps they could be optionally hidden.
Not having the controls visible means for things like increase and decrease font I can't get a reminder of the kb short cuts by hovering the mouse over the button. To get a reminder I have to get into preferences, then into keyboard shortcuts, find and open the the one I've forgotten and click
X my way back to the text - by which time I've forgotten what it was
BR