title: A div with auto resize when changing window width\height
body: <p>I've looked everywhere . 
  and still couldn't come up with sample code of a very "basic" idea:</p>
  
  <p>A div that is taking 90% of the screen size and it is adjusting itself whenever the browser size changes (to take 90% of the relative screen)</p>
  
  <p>The nested divs inside it should resize themselves as well.</p>
  
  <p>Is it even possible?</p>
  
  <p><strong>EDIT</strong>:</p>
  
  <p>Width 90% is not working when I try to re size the screen vertically.</p>