Only works with Firefox 3.6+ as far as I care to know, as this uses native gradients; not a single image is used. Doesn't work well with some GM scripts, dAmn Colors included. Colors can however be disabled, and you can set your own using the CSS itself like so (add the "color:" values, .from is for username, .text is for the message body):

.damncr .self-hl .from span
{
background:-moz-linear-gradient(bottom, #000, #414141 70%)!important;
-moz-border-radius:4px!important;
padding:1px!important;
color:#ffffff!important;
}

.damncr .self-hl .text span
{
background:-moz-linear-gradient(bottom, #000, #414141 70%)!important;
-moz-border-radius:4px!important;
padding:1px!important;
color:#ffffff!important;
}

These two bits of code can be found near the top of the script.

This was meant to be a gradient practice tool, but I quite like how it turned out, as do others, apparently. So it's somewhat public now. Questions? Catch me on dA (http://i-hate-mushrooms.deviantart