Em vs Px and cross browser compatibility

Question

I\'m a CSS newbie and was wondering if there is a benefit using em instead of px when it comes the cross browser compatibility of my CSS.

Answer 1

Strictly speaking the use of em over px isn't really a cross-browser compatibility issue - all browsers support the use of them both for font-sizing.

It used to be advisable to avoid using px for font sizing as the browser with the biggest market share, IE6, wouldn't allow text resizing. It sees px as an absolute value, not a relative value like em, and so wouldn't scale text up or down sized in px.

Depending on your audience you may not need to worry about it. There's some great info on the benefits of the em, and how they can help towards building a fluid layout here: http://www.alistapart.com/articles/fluidgrids/