title: 100% width minus margin and padding
body: <p>I have been searching around but I can't find a solution to apply to my own problem.</p>
  
  <p>I am working on a mobile website and need the input boxes to be 100% width of the screen. But I have <code>padding-left: 16px</code> and <code>margin: 5px</code> that makes the boxes go outside of the screen so I have to scroll to the right to see the end of the box. How do I make the boxes 100% minus the padding and margin?</p>
  
  <p>To try it out: <a href="http://jsfiddle.net/wuSDh/">http://jsfiddle.net/wuSDh/</a></p>