CSS 后代选择器

.ppzx{ margin-top:30px;}
.ppzx .left{ width:253px; float:left;}
.ppzx .right{ width:700px; line-height:38px; color:#1e5836; padding-left:50px; float:left; background:url(home_23.jpg); height:40px;;}


.test{ margin-top:30px;}
.test .left{ width:253px; float:left;}
.test .right{ width:700px; line-height:38px; color:#1e5836; padding-left:50px; float:left; background:url(home_23.jpg); height:40px;;}

<div class="ppzx">
    <div class="left"></div>
    <div class="right"></div>
</div>


<div class="test">
    <div class="left"></div>
    <div class="right"></div>
</div>

其中test 和 ppzx 下面的2个left,right 互不干扰