title: CSS: best way to have dynamic height header and content area to the bottom
body: <p>i'm having a <code>header#masthead</code> and a <code>section#main</code> underneath. The height of the header varies, however I want the <code>#main</code> area of the site to always fill the rest of the window to the bottom. I'd also like to specify a min-height for <code>#main</code> area.</p>
  
  <p>Is that possible with pure css?</p>
  
  <p>Or what's the best way of doing that?</p>
  
  <p>Kind Regards,
  sepp88</p>
  
  <p><img src="https://i.stack.imgur.com/GtvM1.png" alt="enter image description here"></p>