I'm experimenting with @font-face CSS and I'm wondering if I need to embed all different styles of a font (bold, italic, bold italic) in order for all instances of them to work.
For instance, if I embed a font named coolfont.eot on my site and then use it with <em> and/or <strong> tags, will I also need to embed coolfontitalic.eot, coolfontbold.eot and coolfontbolditalic.eot? Or will just the basic version be sufficient?
General principle for all browsers: If the html calls for a variant such as <i>, and the current font doesn't come with the variant, the browser will automatically generate one. (Or, horrible alternative, it will go to the nearest available sans-serif font and use that instead.) This is generally OK for boldface, but questionable for italics. In most font families-- especially serif fonts-- the italic version isn't simply slanted. It uses different letterforms.
Anyway, font embedding really should be restricted to display types such as headers. Definitely not for body text, where it is more likely to annoy the user. In headers, you shouldn't need a variety of letterforms.