Bootstrap下拉式切換類 - 當選項處於活動狀態時更改背景顏色

Question

我有一個使用引導程序的導航欄菜單。一個選項是一個下拉菜單。點擊此選項後會出現灰色背景色。我怎樣才能使用CSS覆蓋這個？

<nav class="navbar navbar-default"> 
     <div class="container-fluid"> 
      <div class="navbar-header"> 
       <button type="button" class ="navbar-tggle collapsed" data-toggle="collapse" data-target="#collapsedNav"> 
        <span class="icon-bar"></span> 
        <span class="icon-bar"></span> 
        <span class="icon-bar"></span> 
       </button> 
       <a href="index.php" style="color: #bcc6cc;" class="navbar-brand"><img src="images/logo.png" alt="Tampa Bay Developers" id="tbdLogo">Tampa Bay Developers</a> 
      </div> 
      <div class="collapse navbar-collapse" id="collapsedNav"> 
       <ul class="nav navbar-nav"> 
        <li class="active2"><a href="#">Products</a></li> 
        <li><a href="#">Services</a></li> 
        <li><a href="#">Support</a></li> 
        <li class="dropdown"> 
         <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-expanded="false">About<span class="caret"></span></a> 
         <ul class="dropdown-menu" role="menu"> 
          <li><a href="#">Articles</a></li> 
          <li><a href="#">Related Sites</a></li> 
         </ul> 
        </li> 
       </ul>     
       <button type="button" class="btn btn-default navbar-btn navbar-right">Contact Us</button> 
      </div> 
     </div> 
    </nav> 

Answer 1

CSS：

.navbar-default .navbar-nav > .open > a, 
.navbar-default .navbar-nav > .open > a:focus, 
.navbar-default .navbar-nav > .open > a:hover { 
    background: red; 
}