I tested this out in a few different browsers and you're right - it displays incorrectly in Firefox and Safari, even though the PDF export still comes out fine. That seems to be due to how those two browsers render the fonts - they increase the size slightly, which pushes the layouts out. I'll add some browser notes to the page here about all that.
UPDATE: I have edited the template to work in all major browsers, so it should be good to go for everyone now.