mui popover 样式多出一条线是怎么回事

<style type="text/css">

                    /*移除底部或顶部三角,需要在删除此代码*/
            .mui-popover .mui-popover-arrow:after {
                position: fixed;
                right: 0px;
                bottom: 0px;
                left: 0px;
                height: 0px;
                            }


    </style>
 <div id="popover" class="mui-popover" >
            <div class="mui-popover-arrow"></div>
            <div class="mui-input-row mui-radio mui-left">
    <label>年假</label>
    <input name="choose" value="年假" type="radio" >
</div>
<div class="mui-input-row mui-radio mui-left">
    <label>事假</label>
    <input name="choose" value="事假" type="radio" >
</div>
<div class="mui-input-row mui-radio mui-left">
    <label>病假</label>
    <input name="choose" value="病假" type="radio" >
</div>



        </div>