div positioning under expanding content div

[dflow]

how do i position a div under a content height dependent  div?

<style type="text/css">
#container {
width:990px;
margin:auto;
position:relative;
} 
#expandingcontent
{height:100%;
position:relative;
}
#under-expandingcontent
{}
</style>
<div id="container >
<div id="expandingcontent">content</div>
<div id="under-expandingcontent">content2</div>
</div>

[jcombs_31]

A div is a block level element, it will natively drop below the previous div unless you are using floats or change the display properties.