17. The computer program product of claim 16 , wherein the outputting further comprises displaying the saved DOM tree, in which DOM elements that differ between the displayed DOM tree and the acquired DOM tree are highlighted.
17. The computer program product of claim 16 , wherein the outputting further comprises displaying the saved DOM tree, in which DOM elements that differ between the displayed DOM tree and the acquired DOM tree are highlighted. 18. The computer program product of claim 17 , wherein the outputting further comprises displaying, in response to a selection of a highlighted DOM element, a CSS property to be applied to the selected highlighted DOM element and a definition location of the CSS property.