Current version of Chrome, but my Windows font settings are set to 110% (system-wide, not browser specific) to make it easier to view text when in a high resolution on a small monitor. I see this issue with various sites that assume a fixed font size which can never change.

If I manually add "font-size: 16px;" to your html,body CSS definition, everything displays properly. The discrepancy is occurring because you are using a fixed pixel height (eg: for the "ten heuristics" div its height is 500px) but letting the browser/system determine the font size.