效果截图（颜色有点丑，请无视）：
<!DOCTYPE html>
<html> <head>
<meta charset="utf-8" />
<title></title>
<style>
* {
margin: 0;
padding: 0;
outline: 0;
} ul,
li {
list-style: none;
} a {
text-decoration: none;
} .nav {
content: '';
display: table;
clear: both;
box-sizing: border-box;
padding: 50px;
} .nav li.list-li {
position: relative;
float: left;
width: 120px;
height: 40px;
line-height: 40px;
font-weight: bold;
border: 1px solid #486b02;
border-right: 0;
background-color: #27AE60;
text-align: center;
box-sizing: border-box;
} .nav>li.list-li:last-child {
border-right: 1px solid #486B02;
} .nav li.list-li ul {
display: none;
position: absolute;
top: 39px;
left: -1px;
width: 120px;
border: 1px solid #8BD400;
border-top: 0px;
border-right: 0;
cursor: pointer;
box-sizing: border-box;
} .nav li.list-li ul.ul-last {
border-right: 1px solid #8BD400;
} .nav .list-li:hover ul {
display: block;
background-color: aquamarine;
color: #fff;
} .nav .list-li a {
display: block;
} .nav li a:hover {
color: #fff;
background-color: blue;
} </style>
</head> <body>
<ul class="nav">
<li class="list-li">
<a href="javascript:;">home</a>
<ul>
<li>
<a>desgin1</a>
</li>
<li>
<a>desgin</a>
</li>
<li>
<a>desgin</a>
</li>
</ul>
</li>
<li class="list-li">
<a href="javascript:;">home</a>
<ul>
<li>
<a>desgin2</a>
</li>
<li>
<a>desgin</a>
</li>
<li>
<a>desgin</a>
</li>
</ul>
</li>
<li class="list-li">
<a href="javascript:;">home</a>
<ul>
<li>
<a>desgin3</a>
</li>
<li>
<a>desgin</a>
</li>
<li>
<a>desgin</a>
</li>
</ul>
</li>
<li class="list-li">
<a href="javascript:;">home</a>
<ul class="ul-last">
<li>
<a>desgin4</a>
</li>
<li>
<a>desgin</a>
</li>
<li>
<a>desgin</a>
</li>
</ul>
</li>
</ul>
</body> </html>