 <p><a href="https://github.com/CJKay/PolyCalc" rel="nofollow">https://github.com/CJKay/PolyCalc</a></p> <p>This is a good start. They have stopped maintaining the project due to most browsers haveing calc available but works well. I have found a couple bugs and fixed them on my sites.</p> <p>If anyone would like to know my fixes please contact me</p>