CSS下拉列表悬停鼠标不起作用

我有一个代码HTML代码：

<div class="wrapper-demo">

 <div id="dd" class="wrapper-dropdown-2" tabindex="1">Sign in with
                    <ul class="dropdown">
                        <li><a href="#"><i class="icon-twitter icon-large"></i>Twitter</a></li>
                        <li><a href="#"><i class="icon-github icon-large"></i>Github</a></li>
                        <li><a href="#"><i class="icon-facebook icon-large"></i>Facebook</a></li>
                    </ul>
                </div>
            </div>

和CSS：

.wrapper-dropdown-2 {
position: relative; 
width: 200px;
margin: 0 auto;
padding: 10px 15px;

background: #fff;
border-left: 5px solid orange;
cursor: pointer;
text-align: left;
cursor: pointer;
outline: none;

}

.wrapper-dropdown-2:after {
    content: "";
    width: 0;
    height: 0;
    position: absolute;
    right: 16px;
    top: 50%;
    margin-top: -3px;
    border-width: 6px 6px 0 6px;
    border-style: solid;
    border-color: grey transparent;

}
.dropdown {
    display:none;
}
.wrapper-dropdown-2:hover ul.dropdown  {
    position: absolute;
    display:block;
    top: 100%;
    left: -5px;
    right: 0px;
    background: white;
    -webkit-transition: all 0.3s ease-out;
    -moz-transition: all 0.3s ease-out;
    -ms-transition: all 0.3s ease-out;
    -o-transition: all 0.3s ease-out;
    transition: all 0.3s ease-out;
    list-style: none;
    opacity: 0;
    pointer-events: none;
}
.wrapper-dropdown-2 .dropdown li a {
    display: block;
    text-decoration: none;
    color: #333;
    border-left: 5px solid;
    padding: 10px;
    -webkit-transition: all 0.3s ease-out;
    -moz-transition: all 0.3s ease-out;
    -ms-transition: all 0.3s ease-out;
    -o-transition: all 0.3s ease-out;
    transition: all 0.3s ease-out;
}

http://jsfiddle.net/pvt3e/

我尝试用鼠标悬停：登录并打开下拉菜单，但不起作用！我无法使用js。因为我对1.8.2有问题，但是我认为我们可以使用CSS找到解决方案