fixed 定位兼容ie6

/*修正ie6 闪烁bug*/
* html,* html body{background-image:url(about:blank);background-attachment:fixed;}



/*对话框 fixed 定位*/
#loginDialog {
    position:fixed;
    top:125px;
    left:50%;
    _position:absolute;
    _top:expression(eval(document.documentElement.scrollTop+125));
    _left:expression(eval(document.documentElement.clientWidth)/2);
}