<p>this is regular text <font size="+2">this is font+2</font>
<span style="font-size:+2">this is css+2</span></p>
<p>this is regular text <font size="+2">this is font+2</font>
<span style="font-size:+2mm">this is css+2mm</span></p>
<p>this is regular text <font size="+2">this is font+2</font>
<span style="font-size:+2cm">this is css+2cm</span></p>
<p>this is regular text <font size="+2">this is font+2</font>
<span style="font-size:+2in">this is css+2in</span></p>
<p>this is regular text <font size="+2">this is font+2</font>
<span style="font-size:+2pc">this is css+2pc</span></p>
<p>this is regular text <font size="+2">this is font+2</font>
<span style="font-size:+2pt">this is css+2pt</span></p>
<p>this is regular text <font size="+2">this is font+2</font>
<span style="font-size:+2em">this is css+2em</span></p>
<p>this is regular text <font size="-2">this is font-2</font>
<span style="font-size:-2">this is css-2</span></p>
<p>this is regular text <font size="-2">this is font-2</font>
<span style="font-size:-2mm">this is css-2mm</span></p>
<p>this is regular text <font size="-2">this is font-2</font>
<span style="font-size:-2cm">this is css-2cm</span></p>
<p>this is regular text <font size="-2">this is font-2</font>
<span style="font-size:-2in">this is css-2in</span></p>
<p>this is regular text <font size="-2">this is font-2</font>
<span style="font-size:-2pc">this is css-2pc</span></p>
<p>this is regular text <font size="-2">this is font-2</font>
<span style="font-size:-2pt">this is css-2pt</span></p>
<p>this is regular text <font size="-2">this is font-2</font>
<span style="font-size:-2em">this is css-2em</span></p>
i tried it in ie and mozilla. both looked to me like it was absolute when using + and ignored when using -
i want the same size as <font size="+2">
and how does that work out if i want to allow the user to use the size that's "browser friendly" ie: if the user adjusts the size in the browser, then the browser will change sizes
You don't mean the browser window, do you? I wouldn't do that if I were you.
I think what you mean is: "the user has set their default type size preference in the browser's settings, so how do I use that to set the type size throughout my site?"
Basically, work everything from 1em. 1.2em would be 120% of the default size. .6em would be 60%. And as I mentioned already, these sizes are relative and nestable. Be careful with that, a simple nesting mistake might drive you insane trying to find.