CSS 美化复选框 - 无图片方式

<div class="check-wrap">
     <input type="checkbox" class="icheck" id="icheck" />
     <label for="icheck" class="ilabel"></label>
</div>

.check-wrap{
     position: relative;
     height: 24px;
     width: 24px;
}
.icheck{
     opacity: 0;
}
.ilabel{        
     border-radius: 3px;    
     cursor: pointer;
     display: block;
     position: absolute;
     top: 0;
     left: 0;
     width: 100%;
     height: 100%;
}
.ilabel:after{
     content: " ";
     border: 2px solid #DDD;        
     display: block;
     font-weight: bold;
     text-align: center;
     border-radius: 3px;
     width: 20px;
     height: 20px;
 }
 .icheck:checked + .ilabel:after{
     content: "?";
     border-color: #3f51b5;
     background-color: #3f51b5;
     color: #fff;
  }
  .icheck:indeterminate + .ilabel:after{
     content: "■";
     color: #3f51b5;
     background-color: #FFF;
     border-color: #3f51b5;
  }

<script>
     var icheck = document.getElementById("icheck");
     icheck.indeterminate = true;
</script>