I know I'm late to the party, but as I was searching for an answer to the same issue, and have since figured it out, I think it makes sense to put the answer here for others to find.
You need to add the line in bold to the UIFILE.txt
<style resid=accountlistss>
element
{
background: argb(0,0,0,0);
alpha:255;
fontface: rcstr(3);
}
...
</style>
The line will probably already be there, but the value will be lower, like 30 or similar.
Hope this helps,
James
