title: Change a css value (left:x) if a browser viewport is <1200px
body: <p>I have a wrap around my content on a webpage that has a width of 1200px. The wrap div is centered in the middle of my page with this css, <code>position:absolute;
      top:0px;
      left:50%;
      margin-left:-600px;
      width:1200px;
      height:auto;
  </code> I need to use jQuery to change the left value from 50% to 0px if the browser viewport width is less then 1200px. Right now on an ipod for example, because the wrap is centered, my content on the left is cut off with no way to scroll to the side. 
  Thank you in advance. </p>