title: CSS width 100% OR max-width in pixels
body: <p>How one could create a CSS rule for width which</p>
  
  <ul>
  <li><p>Uses 100% width by default</p></li>
  <li><p>If 100% width exceeds certain pixel width (let's say 512 px), then the width is clamped down to this pixel width</p></li>
  </ul>
  
  <p>I am not sure about width and max-width relations, or how calc() is supported or could express this. This would need to work with the latest WebKit browsers and Firefox 4. IE8 etc. support not needed</p>