http://stackoverflow.com/questions/585945/how-to-align-content-of-a-div-to-the-bottom-with-css
Relative+absolute positioning is your best bet:
<style type="text/css">
#header { position: relative; }
#header-content { position: absolute; bottom: 0; left: 0; }
</style>
<div id="header">
<h1>Title</h1>
<div id="header-content">Some content</div>
</div>