CSS Detect Styles Overriden

Hi there,

I was just wondering if there are currently any web tools to detect which styles have been overridden.

I am working on a big project doing front-end on an E-Commerce CMS template. After working it through for several months, I have noticed that there are an awful lot of old styles which I have overridden.

I spotted this whilst inspecting with firebug and made a note to myself that after it is all over I shall go back over which rules I no longer need and delete them for efficiency and speed. Does anyone know of software which can pinpoint overridden rules and list them all?