removing header/footer from CHM printout WITH code

How can I remove the header and footer of a CHM printout (from the PRINT button) with HMTL code?

I've tried adding this to the CSS style sheet but it doesn't work:

<style type="text/css">
@media print{
  body{ background-color:#FFFFFF; background-image:none; color:#000000 }
  #ad{ display:none;}
  #leftbar{ display:none;}
  #contentarea{ width:100%;}
}
</style>