code: function computeStyle(elem, prop) {
          if (!win.getComputedStyle) {
            win.getComputedStyle = function(el, pseudo) {
              this.el = el;
              this.getPropertyValue = function(prop) {
                var re = /(\-([a-z]){1})/g;
                if (prop == 'float') prop = 'styleFloat';
                if (re.test(prop)) {
                  prop = prop.replace(re, function() {
                    return arguments[2].toUpperCase();
                  });
                }
                return el.currentStyle && el.currentStyle[prop] ? el.currentStyle[prop] : null;
              };
              return this;
            };
          }
  
          return win.getComputedStyle(elem, null).getPropertyValue(prop);
        }
docs: UTILITY FUNCTIONS __________________________________________________________ 
  Return the current style for an element.
  @param {HTMLElement} elem The element to compute.
  @param {string} prop The style property.
  @returns {number}