<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>下拉菜单</title>
<style>
.select {
margin: 50px 500px;
width: 180px;
text-align: center;
}
.select a {
color: #fff;
text-decoration: none;
}
.select ul,
.select li {
margin: 0;
padding: 0;
list-style: none;
}
.select span {
line-height: 46px;
background-color: #41b1d9;
display: block;
margin-bottom: 20px;
position: relative;
z-index: 2;
border-radius: 5px;
-webkit-transition: all .2s ease-in;
transition: all .2s ease-in;
}
.select span a:after{
content: " ";
display: inline-block;
width: 0;
height: 0;
font-size: 0;
line-height: 0;
border-bottom: solid 6px #fff;
border-left: solid 4px transparent;
border-right: solid 4px transparent;
vertical-align: 1px;
margin-left: 10px;
-webkit-transition: all .2s ease-in;
transition: all .2s ease-in;
}
/*给以整体的阴影和圆角 但是不能overflow*/
.drop {
left: 0;
right: 0;
top: -9999px;
box-shadow: 0 0 2px 0 rgba(0, 0, 0, 0.2);
border-radius: 5px;
position: absolute;
z-index: 1;
-webkit-transform: translateY(-50px);
transform: translateY(-50px);
opacity: 0;
-webkit-transition: all .2s ease-in;
transition: all .2s ease-in;
}
/*给送个下拉助攻*/
.select:hover span{
background-color: #1f93bc;
}
.select:hover span a:after{
-webkit-transform: rotate(180deg);
transform: rotate(180deg);
}
.select:hover .drop{
position: static;
opacity: 1;
-webkit-transform: translateY(0);
transform: translateY(0);
}
/*一个很重要的三角形*/
.drop li:first-child:before {
content: " ";
font-size: 0;
line-height: 0;
margin: 0 auto;
display: block;
box-shadow: 0 0 2px 0 rgba(0, 0, 0, 0.2); /*配合整体一样的投影*/
background-color: #fff;
width: 10px;
height: 10px;
-webkit-transform: rotate(45deg);
transform: rotate(45deg); /*一个正方形倾斜四十五度就是三角了 但是要把下半部分藏起来*/
position: relative;
top: -5px; /*果断的露出上半部分*/
z-index: 1; /*果断的隐藏下半部分*/
-webkit-transition: all .2s ease-in;
transition: all .2s ease-in;
}
.drop li a {
color: #888;
line-height: 46px;
border-bottom: solid 1px #eee;
font-size: 14px;
display: block;
background-color: #fff; /*要有背景色才能盖住呀*/
position: relative;
z-index: 2; /*这里很重要 要挡住三角形的下半部分*/
-webkit-transition: all .2s ease-in;
transition: all .2s ease-in;
}
/*以下两块 控制第一个和最后一个LI要圆角 因为最外边的div没有overflow 也不可以overflow*/
.drop li:first-child a{
border-top-left-radius: 5px;
border-top-right-radius: 5px;
margin-top: -10px;
}
.drop li:last-child a{
border-bottom-left-radius: 5px;
border-bottom-right-radius: 5px;
border-bottom: none;
}
/*hover事件给了li 先改变三角 再改变a*/
.drop li:hover:before{
background-color: #41b1d9;
}
.drop li:hover a {
background-color: #41b1d9;
color: #fff;
}
</style>
</head>
<body>
<div class="select">
<span><a href="javascript:void(0);">鼠标浮上来</a></span>
<div class="drop">
<ul>
<li>
<a href="javascript:void(0);">下拉菜单一</a>
</li>
<li>
<a href="javascript:void(0);">下拉菜单二</a>
</li>
<li>
<a href="javascript:void(0);">下拉菜单三</a>
</li>
<li>
<a href="javascript:void(0);">下拉菜单四</a>
</li>
</ul>
</div>
</div>
</body>
</html>