Embedding Web Fonts - Beginning CSS3 - page 79

Safari 6 and Firefox handle the fonts yet another way. They not only synthesize the bold text, but they also
double the effect when they encounter <b> tags in text that's rendered in the genuine bold font. Look closely at
the word “snail” in the third paragraph in Figure 5-3 . The font is heavier than the rest of the sentence.

Figure 5-3. Firefox not only synthesizes bold text, it doubles the effect with <b> tags

In this example, I've used only bold text, but all browsers handle italic the same way. If a genuine italic face
isn't found, all except older versions of Safari render a synthetic version.
Figure 5-4 shows the difference between synthetic and genuine italic in Firefox.

Regular Bold

Synthetic:

Italic:

Figure 5-4. Comparison of synthetic and genuine italic in Firefox

Failure to synthesize bold and italic in older versions of Safari was an incorrect interpretation of the
specification, as explained in the side bar “To Synthesize or Not to Synthesize.”