(function($) {
  $(document).ready(function() {
    var height  = viewportHeight(),
        article = $('.article');

    if (height < article.height()) {
      article.css({
        'position': 'relative',
        'margin':   '0px auto',
        'top':      0,
        'left':     0
      });
    }
  });

  function viewportHeight() {
    if (typeof window.innerWidth != 'undefined') {
      return window.innerHeight;
    } else if (typeof document.documentElement != 'undefined' && typeof document.documentElement.clientHeight != 'undefined' && document.documentElement.clientHeight != 0) {
      return document.documentElement.clientHeight;
    } else {
      return document.getElementsByTagName('body')[0].clientHeight;
    }
  }
})(jQuery);