find out if a web page used font substitution

Whats a fast and easy way to find out if a web page uses开发者_如何学Python font substitution (like css @font-face)?

Currently I look a the css source code, but that takes to long.

See this answer Firefox plugin for a web developer that shows all resources (js, css, html) as a single unified file?

If you use that firefox plug in it will only take 3 keyboard commands

1. Crtl + Shift + C (view all css)
2. Crtl + f (find)
3. Type in @font-face

Cannot be any quicker then that, unless you want to write some javascript code