Yeah, it is dynamic. But the author also mentioned putting spacer gifs in semantically appropriate containers, so I think it may have been a joke?
Also, as far as I can remember, you could never combine <marquee> and <blink> because only IE supported <marquee> and only the Netscape family of browsers supported <blink>.
I think there is a lot of humor in this article that is maybe a little too subtle.
(Hence, the joke, that to combine the two made you a Great Web Developer, since you knew about such things. The bar was rather low in those days, to be honest.)
> img[src='s.gif'][width='40'] {width: 12px;}