Viewing the CSS in a page with the Firfox browser.  Webmaster 'must have' download

Install in Firefox he add-on

https://addons.mozilla.org/en-US/firefox/addon/60

and install the add-on

https://addons.mozilla.org/firefox/addon/6622

OK restart Firefox, open a webpage and click on the CSS button and choice "View Style Information' or Ctrl-Shift-Y

All info is there