Stylify Me will auto-generate a CSS style guide for any site, including the fonts, colors, sizing, and spacing. Use it to quickly review the styles of various sites efficiently, without having to manually inspect the source code. It also makes it simple to create a style guide for your own designs.Source
Just browsing through the web and found this as the chrome extension plus a desktop app. Thought this might come in handy.
CSS-Shack is a Chrome Web / Desktop App , which allows you to create Layers Styles (just like you would in any other image editing software), and export them into a single CSS file.