Could you try zooming out by holding down the Ctrl key and tapping the - key once or twice. If that is readable, you can leave it that way. Otherwise, a more permanent solution probably requires figuring out why there's no scroll bar to scroll down to that button. Does the mouse scroll wheel work for scrolling (or equivalent, if you have a touchpad)?

Or maybe something is changing the page in a way that pushes the content down. I can't think of any built-in settings that would have that effect, but maybe an add-on is doing it??