弹出层(popover)，点击空白页区可以关闭蒙层却关闭不了弹出的界面

<div class="mui-content">
<a href="#popover" type="button" class="mui-btn mui-btn-submit" id="buttoon">立即报名</a>
</div>

    <div id="popover" class="mui-card" style="position: fixed;bottom:0;margin: 0;padding: 15px;font-size: 16px;width: 100%;z-index: 999;display: none;">  
        <ul class="mui-table-view">          
            <li class="mui-table-view-cell"><span style="font-size:18px;font-weight: bold;">姓名</span>  
                <span class="mui-badge mui-badge-inverted" style="font-size: 16px;color: #2a2a2a;">  
                    <input type="text" class="mui-input-clear" placeholder="您的姓名" style="margin-bottom: 0;text-align: right;border: none;padding-right: 0;">  
                </span>  
            </li>  
            <li class="mui-table-view-cell"><span style="font-size:18px;font-weight: bold;">手机号码</span>  
                <span class="mui-badge mui-badge-inverted" style="font-size: 16px;color: #2a2a2a;width:60%;text-align: right;">  
                    <input type="text" class="mui-input-clear" placeholder="您的手机号" style="margin-bottom: 0;text-align: right;border: none;padding-right: 0">  
                </span>  
            </li>  
            <li class="mui-table-view-cell">  
                <button type="button" class="mui-btn-rod">点击提交</button>  
            </li>                       
        </ul>               
    </div>