I don't know if this works on a Mac, but on a PC CTRL + (i.e press the CTRL key and the + key together) will enlarge the display and conversely CTRL - will make it smaller, which in theory should mean that any 'spill' will be reduced and you won't have to use the scroll bar.
It could also be under tools/options/content if the Mac browsers have an equivalent. I'm sure a Mac user will have an answer for you.