.top-nav{

font-size: 12px;

font-weight: bold;

list-style: none;

border-bottom: 8px solid #dc4e1b;

overflow: auto;

}

.top-nav li{

float: left;

margin-right: 1px;

}

.top-nav li a{

display: block;

line-height: 20px;

text-decoration: none;

background: #ddd;

color: #666;

width: 80px;

        text-align: center;

}

.top-nav li a span{

display: none;

}

.top-nav li a:hover span{

display: block;

}

<ul class="top-nav">

<li><a href="#">首页<span>Home</span></a></li>

<li><a href="#">课程大厅<span>Course</span></a></li>

<li><a href="#">学习中心<span>Learn</span></a></li>

<li><a href="#">关于我们<span>About</span></a></li>

</ul>