var USER_AGENT = navigator.userAgent.toLowerCase();
var IS_IE = USER_AGENT.indexOf("msie") != -1;
var IS_IE6 = USER_AGENT.indexOf("msie 6") != -1;
var IS_IE7 = USER_AGENT.indexOf("msie 7") != -1;
var IS_SAFARI = USER_AGENT.indexOf("safari") != -1;
var IS_FF2 = USER_AGENT.indexOf("firefox/2") != -1;

function css_check(){
	if(IS_FF2){
		document.getElementById('page_util').style.marginTop = '-20px'
	}
}