div with dynamic min-height based on browser window height

Question

I have three div elements: one as a header, one as a footer, and a center content div.
the div in the center needs to expand automatically with content, but I would like a min-height such that the bottom div always at least reaches the bottom of the window, but is not fixed there on longer pages.

For example:

<div id="a" style="height: 200px;">
  <p>This div should always remain at the top of the page content and should scroll with it.</p>
</div>
<div id="b">
  <p>This is the div in question. On longer pages, this div needs to behave normally (i.e. expand to fit the content and scroll with the entire page). On shorter pages, this div needs to expand beyond its content to a height such that div c will reach the bottom of the viewport, regardless of monitor resolution or window size.
</div>
<div id="c" style="height: 100px;">
  <p>This div needs to remain at the bottom of the page's content, and scroll with it on longer pages, but on shorter pages, needs to reach the bottom of the browser window, regardless of monitor resolution or window size.</p>
</div>

Answer 1

Just look for my solution on jsfiddle, it is based on csslayout

html,
body {
  margin: 0;
  padding: 0;
  height: 100%; /* needed for container min-height */
}
div#container {
  position: relative; /* needed for footer positioning*/
  height: auto !important; /* real browsers */
  min-height: 100%; /* real browsers */
}
div#header {
  padding: 1em;
  background: #efe;
}
div#content {
  /* padding:1em 1em 5em; *//* bottom padding for footer */
}
div#footer {
  position: absolute;
  width: 100%;
  bottom: 0; /* stick to bottom */
  background: #ddd;
}

<div id="container">

  <div id="header">header</div>

  <div id="content">
    content<br/>content<br/>content<br/>content<br/>content<br/>content<br/>content<br/>content<br/>content<br/>content<br/>content<br/>content<br/>content<br/>content<br/>content<br/>content<br/>content<br/>content<br/>
  </div>

  <div id="footer">
    footer
  </div>
</div>