It's funny, I've been working with HTML since 1998, and I got 36 (though I do think <font> should've been allowed). I thought I'd do a lot better, but I guess you can accomplish a lot with only a few tags, CSS, and some minimal JavaScript.
Apologies, I knew where and how to look them up. And, seeing the list, only a few I did not know. Some I couldn't remember the abbreviation used in the tag. I just didn't have enough curiosity to actually look them up. :D
I got to 42 and forgot about font (and center, mentioned elsewhere). But quite a lot of tags weren't valid, such as marquee. I wonder if I broke 50 including those.
For what it's worth, I started writing HTML when dates began with the prefix 19... though most of my career has been on the server side.
