@ Banjolover - We have adjusted our fonts for you. It should be working on your machine now. Actually, I prefer Helvetica, too, now that I see it on my Mac. 
Oh. My. Goodness. What a treat. Thank you, Mark. Thank you, Mark. (That’s two thank yous from both of my eyes.)
Now, to be consistent, change it also for "select, input, button, textarea.” It’s currently defined as
font: normal normal normal 99%/ normal arial, helvetica, clean, sans-serif;
Swap Arial and Helvetica around here, too.
And be sure to check this out:
@Mark and Astamoore>>>>>Sorry… even after whatever changes were made, I still get that script-like font on my laptop running Mac OS Leopard… just as before, with the third speaker in the dialog. Do I need to do something with the fonts on the laptop now?? Everything is still looking great on my iMac desktop, running OS Tiger. Any ideas?? As before, all fonts are fine on the print screen of the transcript.
Banjolover
Hit Command-R and reload the page.
Also, just so we’re on the same page, could you link me directly to the page (pun definitely intended) that exhibits the problem?
Update: Never mind. I see italics in some Russian lessons. Displays fine. Like I said, reload the page by hitting Command-R.
The old style sheet is still in Safari’s cache. To force purge it, you need to reload the page. Alternatively, choose Safari > Empty Cache. You may need to quite and relaunch Safari for the change to take effect.
Command-R did the trick for me. Looks great now… all fonts readable. Many thanks to you and Mark for solving this issue for me and other Mac users out there.
Banjolover
Don’t forget to thank Max Miedinger with Eduard Hoffmann for designing Helvetica, and Apple for including it in Mac OS (and its superb text rendering engine).