The marquee tag is an interesting one, it was introduced in early versions of IE, now it's a discontinued feature on HTML 5 (deprecated) working under backwards compatible support, provided by the majority of modern browsers. This tag has the beloved behaviour of scrolling the elements inside of it from a direction to another, just to show them again at the other side after the elments scroll to the end; this behaviour is very simillar to what's seen on TV for "lower third news" or "chyron".
Working marquee tag below:
When deprecated elements are used, different browsers may show them in unexpected and undesired ways, or, maybe the element works as expected, but a warning is shown at the console. Well since the element it deprecated and there are this problems, what are the alternatives?
If you asked on Stack Overflow or similar sites people will simply say you should not use it nor try to replicate this tag because it was deprecated for a (good) reason, because HTML 5 content is not meant for this kind of displaying, et cetera. I disagree with all of these and believe that day by day everyone is trying to improve how to display things, how to make old and new things work better, and if during a point there is a great and simple way of achieving something, this should be proliferated to the max number of people as possbile, if the way of developing it becomes deprecated for whatever reason, that's because there is a better alternative, if not, why the hell did the original form became deprecated? When someone says 'it's just the it is, it shouldn't even exist in the first place because it goes against the principles of X technology' it just sounds as a lazy senseless excuse when this worked, but now it shoudn't work anymore? The same should be valid for every technology/feature.
The original marquee tag is certainly better implemented than my attempt to replicate it because the native browser support will surely beat redoing it with HTML, CSS JS; performance wise and maybe beahaviour, but that is the cost of developing and having something that work the way you want, as opposed to use a tag with the undesired side effects of something deprecated (may lose support in distant future, may break, may show warnings and other annoying things).