Anyone serious about working on their own website should install Chris Pederick's Web Developer browser extension, (and I suggest using it with FireFox).
The toolbar adds all kinds of diagnostic tools for debugging CSS, HTML, DOM, images and more. In-fact, it has so many features, many developers forget what is buried deep inside the toolbar's pull-down menus.
Lets say you wanted to outline all the TABLE CELLS on a page. You could click Tools, then Web Developer, then Outline, then Tables and finally Table Cells, (as the menu below shows);
Instead, if you prefer you can shorten all of clicking to a series of keystrokes.
All of the shortcuts begin with [ALT]+[T]+[W].. so all you need to remember is the 2-3 keys after that. The example above, to Outline Table Cells is [ALT]+[T]+[W]+[O]+[T]+[C].
Here's a few more commonly used ones.
View Image Information ......... [ALT]+TWIV
Outline Block Level Elements ......... [ALT]+TWOB
To learn the shortcuts, start by pressing [ALT]+TW, then look for the bold / underlined characters in each menu item.
To download the toolbar or get support for this great tool,