And for three lines, no more worth the effort, aye? =P
In this code, it might not matter because this is kind of a "set" equation, but for other code, should that line change you then have 2 other places you have to change it. Or, if you have both functions, you then have 5 other places you have to change it. In this case though, yeah, not a big deal, otherwise, yeah.
Yeah, the quick reply was my guess. Honestly, it's because rows/cols is not standardized between browsers. Why not? I have no fucking idea, but it pisses me off. It's the same reason for the issue on Linux and Safari. I'll try to fix it tonight.