[TRINIDAD] how to define media specific styles?

[Paul Spencer]

I would like to to remove buttons from printed copies of a web page. To 
do this using CSS, I simply add @media print{ myStyle{ display:none;}} 
This does appear to where with Trinidad.  I tried the following to no avail:
@media print{
   af|commandButton{ display: none;}
}

@import url(my_print_style.css) print;
Suggestions?

Paul Spencer