Stretch div to bottom of screensize, but allow scrolldown - css

Question

On load I'd like to load the topsection div with a bg image and have it take up the entire screen, but then I have content below it which you can scroll down to. The div should size itself to the window screen only on load and not remain like that on scrolldown. I cannot give the div a position:absolute; either.
I'm banging my head on this one. I've tried a ton of different things
Here is my html:
<div id="topsection" class="row bgimage ">
<div id="logomain" class="mainlogo ">
<div class=" floorplanbuttoncontainer helvetical">
<ul>
<li>Residence A - Duplex</li>
<li>
Residence D - Simplex</li>
</ul>
</div><!-- end floorplanbuttoncontainer -->
</div><!-- end logomain -->
Here is my css for the background image:
.bgimage {
background: url(images/image.jpg) no-repeat center center fixed;
background-size: cover;
.mainlogo {
margin:0 auto;text-align:center;width:100%;height:488px; /*I think this height is messing things up */
background-image:url(images/picture.png);background-repeat:no-repeat;
background-position: center;
}

Answer 1

In order to set a div to take up the entire screen you need to set the height of the body and html element to 100%. You also have to remove the padding and margin from them. Then you create a wrapper class to encase your content and assign it your background-image. Then all ya' gotta do is create the content below your full screen image to scroll into!
Fiddle
Edit
If you run the snippet below and hit full page you can see how it works.
body, html {
height: 100%;
margin: 0;
padding: 0;
}
.wrapper {
min-height: 100%;
background: red;
}
.full {
width: 100%;
}
.footerThing {
width: 100%;
height: 200px;
background: blue;
}
<div class="wrapper">
<div class="full">
asd
</div>
</div>
<div class="footerThing">
</div>

Answer 2

Modern browsers: a simple way is to use vh units to get the Viewport Height
Just to simplify: jsBin demo
<div id="home" class="container full">
<h1>HOME</h1>
</div>
<div id="about" class="container">
<h1>About us</h1>
<p>Content</p>
</div>
CSS:
.container { min-height:400px; }
.full { height:100vh; }
Crossbrowser: use % instead of vh and simply add html, body{height:100%;} jsBin demo