// IE 
if(document.all){ 
$height = document.body.clientHeight;
$width = document.body.clientWidth;
$top = ($height/2)+240;

document.writeln("<style type='text/css'><!--");
if($top <= 480){
document.writeln(".commform{position:relative;top:0px;}");
} else{
document.writeln(".commform{position:relative;top:-" + $top + "px;}");
}
document.writeln("--></style>");
} 
// DOM
else if(document.layers || document.getElementById){ 
$height = window.innerHeight;
$top = ($height/2)+240;
document.writeln("<style type='text/css'><!--");
if($top <= 0){
document.writeln(".commform{position:relative;top:0px;}");
} else{
document.writeln(".commform{position:relative;top:-" + $top + "px;}");
}
document.writeln("--></style>");
}