复选框边框样式,去掉立体感
<span style="border: 1px solid #666666; overflow: hidden;width:12px; height:12px">
<input type="checkbox" name="checkbox" value="" style="position: absolute; margin: -5px" /></span>
<input type="checkbox" name="checkbox" value="" style="position: absolute; margin: -5px" /></span>