http://www.i3physics.com/blog/2010/07/dsfsdf/
Here is an example.
The part where it said "PHP" (the right top corner) remained as slim as it was. here is part of the css code
.wp_syntax_lang {
background-color:#3c3c3c;
position:absolute;
right:0;
padding:1px 10px 3px;
color:#ddd; font-size:9px; font-weight:800;
text-transform:uppercase;
-moz-border-radius-bottomleft:5px;
-webkit-border-bottom-left-radius:5px;
border-radius-bottomleft:5px;
}
I tried bold, bolder, 700, 800, 900 and is not working under FF.