I know this is something of an old thread, but I believe I see the problem.
Just glancing through the source code of each website (CS and BP), I see that CS is almost entirely built out of HTML tables, and the CSS on the page is mainly used to change what stuff looks like when it uses or is within certain tags (e.g., "body", "link", "link visited", "link hover").
a:link, body_alink
{
color: #000000;
text-decoration: none;
}
a:visited, body_avisited
{
color: #000000;
text-decoration: none;
}
a:hover, a:active, body_ahover
{
color: #5555FF;
text-decoration: underline;
}
This chunk of code means that every link in the <body></body> tags is in black font with no underline, except when hovered over. Then it turns blue and gets an underline.
BP.net uses a much more updated coding system that makes full use of what the CSS coding language has to offer. Instead of using tables, they use <div></div> tags. These streamline coding, can be nested into a logical system of wrappers or divided into blocks, and, most importantly, they can be assigned "classes", which are used to customize the tags, as well as anything enclosed in them. This means that instead of having just a header, a footer, and a hundred tables inside the <body> tags that may each need to be configured separately, you can customize what every part of the site looks like by writing relatively few classes just once, and then assigning them to whatever <div> tags they need them to.
All they have to do to get links in posts to show up underlined, but leave the links elsewhere undecorated, would be to use a different class for the <div></div> tag(s) wrapping the posts. The frustrating thing is, they're put all of their classes on externally-hosted source pages, which are tough for me to access. I'll try to get to them later.
I'm a tad too rusty at CSS to do it myself at the moment, but classes are pretty basic CSS. CS.com even currently uses some, like the "highlight" class....
.highlight
{
color: #FF0000;
font-weight: bold;
}
The hardest part would be converting the "table soup" system CS.com is currently using into updated CSS with <div></div> tags. From there, getting underlined links in one place and no-underlined links in another would be a piece of cake.