当在移动设备上观看时，3个并排的div不会垂直叠加

Question

我有三个div并排(在一个显示器上)，每个都有一个背景图像(通过CSS)和文本浮动在每个背景之上(通过html)。这三个div被一个容器div包围，该容器div将三个div都放在页面的中心。我希望这些div在移动设备上看到时垂直叠加。有什么建议吗？下面是测试页面：id=649

这里是html (CSS在下面)：

<div style="margin: 0 auto; width:744px;">
<div style="float: left; width: 248px;">
<div id="parchment">
<img id="parchmentbg" src="http://worddiva.com.s40758.gridserver.com/wp-content/uploads/2014/07/Parchment-Grade-Orange.png"/>
<p id="text">
<span class="storytellingorange"><strong>Editorial</strong></span>
– Credit Union
– Wine &amp; Travel
– Arts &amp; Letters
– Alternative Energy
</p>
</div>
</div>

<div style="float: left; width: 248px;">
<div id="parchment">
<img id="parchmentbg" src="http://worddiva.com.s40758.gridserver.com/wp-content/uploads/2014/07/Parchment-Grade-Orange.png"/>
<p id="text">
<span class="storytellingorange"><strong>Editorial</strong></span>
– Credit Union
– Wine &amp; Travel
– Arts &amp; Letters
– Alternative Energy
</p>
</div>
</div>

<div style="float: left; width: 248px;">
<div id="parchment">
<img id="parchmentbg" src="http://worddiva.com.s40758.gridserver.com/wp-content/uploads/2014/07/Parchment-Grade-Orange.png"/>
<p id="text">
<span class="storytellingorange"><strong>Editorial</strong></span>
– Credit Union
– Wine &amp; Travel
– Arts &amp; Letters
– Alternative Energy
</p>
</div>
</div>
</div>

这里是CSS:

#parchment
{
    height:133px;
    width: 744px;
    position:relative;
    margin-left: auto;
    margin-right: auto;
}

#parchmentbg
{    
    position:absolute;
    left:0;
    top:0;
}
#text
{
    z-index:100;
    position:absolute;
    line-height: 1.3em;  
    left:10px;
    top:-15px;
}

Answer 1

#parchment的父div具有固定的宽度。这会导致子div不会相互叠加，因为父div不会变小。