It's a "non-conforming feature" but it's still a part of WhatWG's standard as obsolete, including what it should render as: https://html.spec.whatwg.org/multipa

It's a "non-conforming feature" but it's still a part of WhatWG's standard as obsolete, including what it should render as: https://html.spec.whatwg.org/multipage/rendering.html#the-marquee-element-2 https://html.spec.whatwg.org/multipage/rendering.html#the-ma... and https://html.spec.whatwg.org/multipage/obsolete.html#the-marquee-element https://html.spec.whatwg.org/multipage/obsolete.html#the-mar...