纯css实现 switch开关

<!-- 直接看代码，利用了css3兄弟选择器 -->
<!-- html -->

<button class="switch">
     <input type="checkbox">
     <span><i></i></span>
</button>    

/*scss*/

.switch {
  position: relative;
  width: 50px;
  height: 25px;
  background-color: #fff;
  border: none;
  outline: none;
  i {
    position: absolute;
    left: 0;
    top: 0;
    display: block;
    height: 23px;
    width:23px;
    border-radius: 50%;
    border: 1px solid #dadada;
    background-color: #fff;
    transition: all .2s;
  }
  span{
    position: absolute;
    display: block;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    border: 1px solid #dadada;
    border-radius: 25px;
    z-index: 0;
  }
  input{
    position: absolute;
    top: 0;
    left: 0;
    width: 50px;
    height: 25px;
    margin: 0;
    padding: 0;
    opacity: 0;
    z-index: 9999;
    &:checked + span{
      background-color: #58ad2c;
      border-color: #58ad2c;
    }
    &:checked + span i{
      background-color: #fff;
      border-color: #58ad2c;
      left: 25px;
    }
  }
}