Use Inline CSS in javascript.
function PrintPage()
{
var sOption="toolbar=yes,location=no,directories=yes,menubar=yes,scrollbars=yes,width=900,height=300,left=100,top=25";
var sWinHTML = document.getElementById('divPrint').innerHTML;
var winprint=window.open("","",sOption);
winprint.document.open();
winprint.document.write('<html><head><style type="text/css">');
winprint.document.write('body,td,th{font-family:Arial, Helvetica, sans-serif;font-size:10px;color:#000000}');
winprint.document.write('.style1 {font-size:11px; font-weight:bold; color:#000000; }');
winprint.document.write('.style2 {font-size:11px; font-weight:bold; color:#FFFFFF; }');
winprint.document.write('</style></head><body onload="window.print();">');
winprint.document.write(sWinHTML);
winprint.document.write('</body></html>');
winprint.document.close();
winprint.focus();
}
Here divPrint using the inline css which was written in inside script. It's working one.