如何在css中创建自定义复选框

input[type="checkbox"].hidden {
  display: none;
}

.demoCheck {
  border: 1px solid #ddd;
  width: 25px;
  height: 25px;
  display: block;
}

input[type="checkbox"]:checked.hidden + label {
  background: url(http://www.clipartsfree.net/vector/small/23493485345_Clipart_Free.png) center center no-repeat;
  background-size:cover;
}

<input type="checkbox" class="hidden" id="demo" >
<label for="demo" class="demoCheck demoCheckLabel"></label>