If he had used 2 significant figures (tenths of a percent), his size would be off by less than a dot at 1200 DPI. If he had used 3 significant figures (hundredths of a percent), his size would be off by just about 1 dot at 4800 DPI. Since web browsers tend to round to the nearest pixel on ~100 DPI screens, yes, I’d say 19 signifiant figures is more than a little overkill.
Then again, you never know when you might need to print your web page at billboard size and maintain down-to-the-micron precision.
AFAIK even modern webkit browsers round up at the 1000th's place, so that's where I stop. I'm guessing those are value spit out by some sort of CSS calculator as part of a framework or similar. Having said all that, it's certainly "future proof."
that’s a casualty of using TextMate to parse calculations with Google Calculator. I used to use Calculator.app, but started relying on TM because it’s so easy to use.
I will never, for the love of absurdity, never use 20 decimals for what should be a simple value.
Can't we just round it up?