Can you reproduce the problem independently on your own? You're saying it's a complaint from a particular user.
It can be as simple as that particular user having hit the Ctrl+ key combination by mistake and now the page has Zoomed to approximately 125%. The chrome on Chrome and Safari gives no clue as to the Zoom level or type of zoom (page zoom or text zoom) unless you go into the menus.
Please come back and report if this does, indeed, prove to be the problem.