In various browsers, when a specific font is used (e.g. – Helvetica Neue), if that font is not found, the first font in the immediate family is used. So if I were to specify that Arial Narrow was the base font style for an element and my reader did not have this font, it would travel to the first available Arial font the system could find.
As an exercise, many sites like the Helvetica fonts (particularly the ‘Neue’ and ‘Condensed’ versions). They typically specify font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; believing that the browser will travel along this particular path and each font should be yummy with the first listed being the yummiest. However, Firefox/IE/Chrome (so I assume webkit browsers) all will fail to the find the specific Helvetica font required and move directly to the first font they encounter in the Helvetica family. One would think this would be Helvetica, but on my system it was defaulting to Helvetica 95 Black. I even tried renaming the font file to see if that was the cause, and no matter the filename, the result was that the page would default to Helvetica Black. I’ve found this to be the case with Arial as well.
So other than attempting to account for every single flavor of Helvetica, Arial, Verdana, Tahoma, ad infinitum, is there a way to force the browser to stop “guessing” at the family and accept only the exact font in question?
For starters, here’s a description of the font matching algorithm as outlined in the CSS 2.1 specification (or CSS 3, if you prefer). This is a tricky issue though, as is evidenced by the disclaimer before the algorithm’s details are outlined:
Also, note that you must enclose any font name containing whitespace with either single or double quotes, as per section 15.3.