答案 0 :(得分:3)
<style type="text/css">
.bx{
width: 73px;
height: 73px;
background: transparent url("top.png") no-repeat;
}
.bx.yellow{background-color: yellow}
.bx.green{background-color: green}
</style>
和
<div class="bx"></div>
<div class="bx yellow"></div>
<div class="bx green"></div>