今天给大家带来一款纯css3实现的鼠标悬停动画按钮。这款按钮鼠标经过前以正方形的形式，当鼠标经过的时候以动画的形式变成圆形。效果图如下：
实现的代码。
html代码：
<div>
<span></span>
</div>
css3代码：
body
{
background-color: #333;
}
div
{
width: 200px;
height: 200px;
margin: 0 auto;
}
span
{
position: relative;
width: 180px;
height: 180px;
display: block;
margin: auto;
top: 25px;
border: 20px solid rgba(255, 255, 0, .25);
background-color: rgba(124,155,13,1);
-webkit-transition: .5s;
-moz-transition: .5s;
-ms-transition: .5s;
transition: .5s;
border-radius: 30px 0px 30px 0px;
}
span:before, span:after
{
position: absolute;
display: block;
background-color: #fff;
border-radius: 10px;
margin: auto;
top: 0px;
bottom: 0px;
left: 0px;
right: 0px;
}
span:before
{
width: 100px;
height: 10px;
content: "";
} span:after
{
width: 10px;
height: 100px;
content: "";
} div:hover span
{
-webkit-transform: scale(.5) rotate(45deg);
-moz-transform: scale(.5) rotate(45deg);
-ms-transform: scale(.5) rotate(45deg);
transform: scale(.5) rotate(45deg);
border-radius: 110px;
background-color: rgba(112,18,255,1);
}