On StackOverflow, we have a dhtml tag, which is quite useless. DHTML is "is an umbrella term for a collection of technologies used together to create interactive and animated web sites by using a combination of HTML, JS and CSS".
It's just a collection name for HTML + JS/CSS. That means every question tagged with dhtml has also a html tag and one/both of javascript and css, which means the tag doesn't make sense at all.