If I use the font forte in a stylesheet like this: font-family: Forte, Arial, Helvetica, sans-serif; What is the worst case scenario if a user does not have the font forte? Is it just that Arial will be used instead or is there something worse that might happen?
If a user does not have the font on their computer, it will go down the list until it finds one it does - however, you should design the site assuming the vast majority of your users do not have "forte" - and I personally wouldn't included such an uncommon font in a css list. I have about 6,000 fonts and don't have "forte" - and unless you are deactivating the font when you view your site, you aren't seeing the site as the majority of your visitors are.
Why not have this extra "bonus" style for the few people that do have this font as long as the page looks fine with Arial at the same time? Is Forte really not that common? I don't have many fonts on my computer, but I do have Forte. By the way, the header images of a particular site use this font called Forte, so I thought it might look good to have this used in the CSS for the sub headers.
Different fonts obviously display differently and can affect you page layout. The real problem is looking at your site with such an uncommon font because you won't see how 99% of your visitors are seeing the site. Any changes you make, you would have to make sure it was viewing correctly without the font. You can use any font for a graphic, you just don't see them used with css. If you want to include a font that maybe 1% or 2% or your visitors will ever see (it's a commercial font you purchase), then go ahead. I just wouldn't want the hassle of editing the css or disabling a font every time I made a change to the page.
Well, in this case the headers are on a line all by itself and no layout changes really take place when switching between Arial and Forte. So, as far as I can tell it's not going to really cause any problems. One further question I have is whether it is possible to detect if the user has the font or not and to display an image instead of the font if they do not have the font installed.
No! What the user has or hasn't on his machine is none of your business—or mine, for that matter. That's why you use font preferences (yours). You're saying, "if you have it, please use xyz font, failing that, use uvw font, and finally, whichever sans-serif font you like." Keep in mind the user can reject your preferences from the get-go without any need to tell you it's happening. cheers, gary
If the user doesn't have the last-resort font installed, it could vaporize their PC. Seriously, I make extensive use of sIFR on my sites - works like a charm and it's w3c-approved!
A vote for sifr from me too. Not only is it useful for using "custom" fonts, but you can also use it to just get a prettier rendering of Arial or something common when you have large headings.