在firefox上无法居中

IE下正常，FIREFOX无法居中:cry:

HTML:

body {
	border: 0;
	margin: 0;
	padding: 0;
	color: #555;
	font: 12px Tahoma, sans-serif;
	text-align: center;
}

#main {
	margin: 0px;
	width: 600px;
}

#mainleft {
	float: left;
	width: 190px;
	padding: 0px;
	vertical-align: top;
	text-align:center;

}

#mainright {
	float: right;
	width: 400px;
	text-align: left;
}

 

谢谢