Container div height not resizing? - html

Question

I know there are a hundred and one questions about autosizing a div's height but no suggestions seem to work for me which leads me to believe I'm missing something obvious. Basically I have a container Div, then another smaller div inside (absolutely positioned) and in side that one I have X about of div boxes being created (relatively positioned). The problem is that the height of the main container div won't stretch with it. Any help? Thanks!
.mainContainer{
position: relative;
width:800px;
height:auto;
padding-top:10px;
margin-left: auto;
margin-right: auto;
border-style:solid;
border-width:2px;
}
.smallerDivInsideMainDiv{
position:absolute;
left: 20px;
top: 50px;
width: 600px;
}
.divsThatAreOverflowing{
position: relative;
margin-top:20px;
border-style:solid;
border-width:1px;
}

Answer 1

From what I know, you can't have an absolutely positioned element inside a relatively positioned element and attempt to have the parent height adjust to the absolute child. If you're only using it for positioning with left and right, use margins instead.
<style>
.mainContainer{
width: 800px;
height: auto;
padding-top: 10px;
margin-left: auto;
margin-right: auto;
border-style: solid;
border-width: 2px;
background: #999;
}
.smallerDivInsideMainDiv{
margin-left: 20px;
margin-top: 50px;
background: #CCC;
width: 200px;
}
.divsThatAreOverflowing{
margin-top: 20px;
border-style: solid;
border-width: 1px;
background: red;
height: 300px;
width: 100px;
}​
</style>
<div class="mainContainer">
<div class="smallerDivInsideMainDiv">
<div class="divsThatAreOverflowing"></div>
</div></div>
Here the parent is dark grey, and smaller div inside is light grey, with the overflowing div as red. When it changes height, both of it's containers will adjust.

Answer 2

You should use relative position for the smallerDivInsideMainDiv too and the main div will auto-resize with the total sizes of the contained divs (with their margins too), but it will ignore your "top: 50px;". For that you could add an empty div
<div style='height: 50px;'></div>
after smallerDivInsideMainDiv while still in mainContainer, something like:
.smallerDivInsideMainDiv{
position:relative;
<div class="mainContainer">
<div class="smallerDivInsideMainDiv">
<div class="divsThatAreOverflowing">x1</div>
<div class="divsThatAreOverflowing">x2</div>
</div>
<div style='height: 50px;'></div>
</div>