Bootstrap 手风琴切换在第一次页面加载时错误地加载内容符号 (+/-)

Bootstrap accordion-toggle loads the content symbol(+/-) wrongly on first time page load

您好,我在 visualforce 页面上使用了以下手风琴切换代码。可折叠切换工作正常,但第一次加载页面时除外。在 pageload/Refresh 上,折叠面板显示时带有符号“-”,而不是预期的内容“+”。有人可以帮我吗?

Visualforce 页面代码:

<a hef="#" class="accordion-toggle" data-target="#collapse1" data-toggle="collapse">&nbsp; Data Panel 1 </a>
    <div id="collapse1" class="panel-collapse collapse">
       <ul style="list-style-type:none">
             <li> <a hef="#" class="accordion-toggle" data-target="#collapse9" data-toggle="collapse">&nbsp;&nbsp; Data Panel 2</a>
                <div id="collapse9" class="panel-collapse collapse">
                      <ul style="list-style-type:none">
                           <li><font style="color:#337ab7"> Description</font></li>
                       </ul>
                </div>
              </li>
              <li> <a hef="#" class="accordion-toggle" data-target="#collapse8" data-toggle="collapse">&nbsp; &nbsp;Data Panel 3</a>
                <div id="collapse8" class="panel-collapse collapse">
                     <ul style="list-style-type:none">
                           <li><font style="color:#337ab7"> Node 1</font></li>
                           <li><font style="color:#337ab7"> Node 2</font></li>
                           <li><font style="color:#337ab7"> Node 3</font></li>
                      </ul>                                                                                              

                </div>
             </li>
         </ul>
     </div> 

CSS 风格:

  .accordion-toggle:after {
                    font-family: 'Glyphicons Halflings';  
                    content: "\e082";   <!-- taken from bootstrap.css -->
                    float: left;          
                }

                 .accordion-toggle.collapsed:after {
                    content: "\e081";   <!-- taken from bootstrap.css -->
                }

                a 
                {cursor: pointer; }

在标记中将它们设置为 class="accordion-toggle collapsed"。这是它们最初将设置为折叠状态并显示 + 图标。

http://codeply.com/go/909KJuqOs5