Safari Font Problem

First off, make sure your system software is up to date.

Second, try trashing your preferences (home folder > Library > Preferences). If that doesn't work, check your preferences in Safari, as well as your Font selections for the operating system (if you have TinkerTool installed, check the fonts there). Try changing the fonts in all possible cases and see if this fixes the problem. You may have to restart Safari each time.

Don't forget, Safari is still in beta. Have you noticed this problem with other websites? (In other words, not pages within the site with the attachment)

Safari v64 has been leaked around. If you can hunt that down to see if the problem remains, do so before you report anything. If you have determined the issue is not from the fault of your computer with both versions or Safari v62, if you cannot acquire v64, then report it.