If you want to use a different font size than all font information would have to go in the custom css tab. Anything in Custom CSS overwrites the other settings.
tanks - I was a'feared of that :)
If you do a View Source of your profile, you can probably get the code on the fonts from there and copy and paste the information in the custom css tab. Then you can probably fiddle with it a little to get what you need.
Here are the font codes from your profile:
#sitesearch h3, #homelink, #member-nav {font-family:tahoma,geneva,arial, helvetica,clean,sans-serif;}
#sitesearch h3, #homelink, #member-nav {font-weight:900;}
#sitesearch h3, #homelink, #member-nav {font-style:normal;}
#sitesearch h3, #homelink, #member-nav {font-variant:normal;}
#sitesearch h3, #homelink, #member-nav {color:#000000;}
#sitesearch a, #homelink a, #member-nav a {color:#000000;}
#corp-nav {font-family:tahoma,geneva,arial, helvetica,clean,sans-serif;}
#corp-nav {font-weight:900;}
#corp-nav {font-style:normal;}
#corp-nav {font-variant:normal;}
#corp-nav {color:#000000;}
#corp-nav a {color:#000000;}
#subnav {font-family:tahoma,geneva,arial, helvetica,clean,sans-serif;}
#subnav {font-weight:900;}
#subnav {font-style:normal;}
#subnav {font-variant:normal;}
#subnav {color:#000000;}
#subnav a {color:#000000;}
.header {font-family:tahoma,geneva,arial, helvetica,clean,sans-serif;}
.header {font-weight:bolder;}
.header {font-style:normal;}
.header {font-variant:normal;}
.header {color:#000000;}
.header a {color:#000000;}
.body {font-family:tahoma,geneva,arial, helvetica,clean,sans-serif;}
.body {font-weight:bolder;}
.body {font-style:normal;}
.body {font-variant:normal;}
.body {color:#000000;}
.body a {color:#000000;}
Please do not change font size except as necessary to make the font appear to be the same size as the standard font. In other words, please try to follow our standard. This is an accessibility issue. People with vision impairments often increase font size in their web browser. If people are too dramatic with their font size changes (which people tend to be, when given the chance), fonts may become too large to be practical. With our fixed-width column layout, larger fonts can also sometimes "break" the layout (particularly in IE6). Of course, there are many different ways people can make their profile page illegible and this is only one. If you know what you're doing and your changes are reasonably subtle, go for it!