一个DIV位于另一个div的右下角

<style type="text/css">
.main{
500px;
border:#000 solid 1px;
height:500px;
position:relative;}

.tab{
cursor: pointer;
display: inline-block;
height: 22px;
vertical-align: bottom;
bottom: 5px;
position: absolute;
right:5px;
}
</style>

<div class="main">
<div class="tab">ddds</div>
</div>