You sure can! They all have inline defaults like `<span>` so set some CSS baseline on them as needed, but this is like the best kept secret of HTML or something? Unknown tags will become `HTMLUnknownElement` and behave like a span.

Edit: the reason for avoiding this in the past was name-spacing. But the standard says you can use a hyphen and then you're OK, native elements won't ever use a `-`.

Edit 2: also it's great because it works fine with CSS selectors too. Write stuff like `<image-container>` in plain HTML docs and it's fine.

Edit 3: but also `<albums>` tags and etc which won't be adopted into the HTML standard soon work too if they don't conflict with element names, and the rare case that they might be adopted in the future as an element name can be resolved with a simple text search/replace.

Edit 4: This all really has little to do with javascript, but you can use `querySelector` and `querySelectorAll` with any of these made up names the same as any native name too.

It's very nice to write. I used and liked vue for a little while when it was needed(?) but modern HTML fills that gap.

Nitpick: If a nonstandard element name contains a hyphen (and is otherwise a syntactically valid custom element name), the element's DOM object is an instance of HTMLElement, not HTMLUnknownElement.

Quoth the standard: "The use of HTMLElement instead of HTMLUnknownElement in the case of valid custom element names is done to ensure that any potential future upgrades only cause a linear transition of the element's prototype chain, from HTMLElement to a subclass, instead of a lateral one, from HTMLUnknownElement to an unrelated subclass."