Font Size - Whats does em do?

[Phil99]

Hi

I'm creating a stylesheet at the moment. I need to set the font size which seems ok using:

font-size: 7pt;

But i've also seen the following statement used:

font-size: 1em;

Please can you confirm when em should be used and what affect it has on the font size.

Many Thanks

Phil

 

[Rieekan]

one em is equal to the current font size of the current element

Basically, an EM is the width of the letter M for your current font size. Generally, EMs are used for font sizing instead of points so users that have their browser text size set to something other than the default can see the text clearly. If you set all of your fonts to point sizes, visually impaired people may have a difficult time in viewing your website.

- George