html结构
css代码，:before负责颜色，:after是那个白色小圆点，切换时的过渡效果用css3的动画实现。
.switch{
display:none;
}
label{
position:relative;
display: block;
padding: 1px;
border-radius: 24px;
height: 22px;
margin-bottom: 15px;
background-color: #eee;
cursor: pointer;
vertical-align: top;
-webkit-user-select: none;
}
label:before{
content: '';
display: block;
border-radius: 24px;
height: 22px;
background-color: white;
-webkit-transform: scale(1, 1);
-webkit-transition: all 0.3s ease;
}
label:after{
content: '';
position: absolute;
top: 50%;
left: 50%;
margin-top: -11px;
margin-left: -11px;
width: 22px;
height: 22px;
border-radius: 22px;
background-color: white;
box-shadow: 1px 1px 1px 1px rgba(0,0,0,0.08);
-webkit-transform: translateX(-9px);
-webkit-transition: all 0.3s ease;
}
.switch:checked~label:after{
-webkit-transform: translateX(9px);
}
.switch:checked~label:before{
background-color:green;
}