That's because the links are already bold, they're set that way with this element of your stylesheet:
QUOTE
#submenu p,
#userlinks p,
#userlinksguest p{
background: transparent !important;
border: 0 !important;
font-size: 10px;
font-weight: bold;
letter-spacing: 1px;
margin: 0 !important;
padding: 7px 0 7px 0;
text-align: right;
}
You'll have to do some other style editing in the skin template to make this more bold. Maybe try changing the rules_link template to this:
CODE
<a href="$url" style="font-size: 12px">$title</a>