Question : Safari ems and pixels

I was just doing some experimentation and was hoping someone could explain why the following is happening. If I define a css rule for a paragraph as .5em, my understanding is that all browsers will render this as 8px (since the default font size is 16px) but when I check the computed size by using Inspect Element I see the ocmputed size is 9px. In Firefox, it computes to 8px.

Answer : Safari ems and pixels

All browsers render EMs differently.  They have different algorithms for calculation how wide an EM is... and such is the case that some browsers will render things a little differently.  And if a user has specified a different default font size in their browser settings, then everything gets knocked up/down accordiingly.  It's kind of a pain in the arse.

You only want to use EMs if you are not going for a pixel-perfect layout.  Otherwise, if you want things to show up EXACTLY the same in all browsers, use pixels.

Cheers.