Can't use scroll down arrow

When I open a PDF in Safari, the down arrow is covered by the window resizing area which basically means I can't scroll down. When I open up the same PDFs in Chrome, this doesn't happen. I've tried uninstalling Reader and re-installing and I still have the same issue. I've had this issue for several updates of Reader. I know the easy fix would be to just use Chrome but I'd like to figure out why it is doing this. Any ideas?