Internet explorers all versions calculate different dimensions from other browsers about susy

[mirisuzanne]

If you do the math, this makes perfect sense. And, in this case, IE is giving you the number you actually are looking for. This isn't a bug anywhere: not in Susy, not in IE, not in Chrome, not anywhere. This is simply an issue presented by the medium (specifically a result of the mediums coolest features), and browsers are all still working to find the best solution.

The problem is sub-pixel rounding, and it will be an issue in any percentage-based design. There is a great article on it here:

http://ejohn.org/blog/sub-pixel-problems-in-css/

The problem with any hack is that it amounts to the sort of browser sniffing that will leave you hanging as soon as a new version is released.

But the point of designing with percentages rather than pixels is to embrace flexibility. If you are designing for flexible situations, learning to manage a few pixels difference between browsers is no problem. Don't fight it, embrace it.