It is possible to define a font as "normal" in the @font-face, and the use it as bold and/or italic in other font-family rules, expecting the renderer to artificially embolden and/or slant the font (if no other appropriate bold/italic @font-face was defined).
Whether the renderer will actually do this, or just use the normal font, or use any other bold/italic font available, that's a different matter. And how easy it is to detect this situation is yet another different matter
