z-index

クリックで全選択状態になります。

.sample { z-index: 値; }

.sample-box{
width:700px;
height:300px;
position:relative;
}

.sample1{
width:300px;
height:100px;
background:#0066cc;
position:absolute;
z-index:1;
top:0;
left:0;
}

.sample2{
width:300px;
height:100px;
background:#99cc00;
position:absolute;
z-index:2;
top:60px;
left:200px;
}

<div class="sample">
<div class="sample1">.sample1</div>
<div class="sample2">.sample2</div>
</div>

値/プロパティ値

-