so it turns out nobody has needed to use div tags for like six years now

Go to whatever you personally use to write HTML, and type in the following:

<like-this></like-this>

No, really, go do that. Do that, and then put it in an HTML file, and then write styling for it, selecting it like you would a normal span tag like-this {}, and then realize that yes, that actually works. Genuinely.

An example of like-this, as a tag, being styled green with white text reading "huh. what do you mean this just works like that. excuse me" — ???

…

What do you mean that just works.

WHAT DO YOU MEAN THAT JUST WORKS—

how

Okay, here are, as far as I can tell, the rules.

It has to have a hyphen; <this-tag> works, <thistag> doesn’t.
You cannot self-close them; <this-tag /> won’t work.
They have to start with a lowercase letter.
They have to not have uppercase letters.
There are no other limits.

another example, with a tag using an eggplant emoji; the joke is penis — my sexuality is this exact tag but with a lesbian flag for a background

It, honest to god, just works. CanIUse implies that this has limited availability for the really specific reason I imagine you’d originally want to use it, but as far as I can tell, if you’re literally just using it as a <div> drop-in replacement, that’s it. It goes in, you style it like you’d style a normal tag, it just works like that, on every browser not still in use at your local tax agency.

They’re technically all <span> tags, thus me having to put display:block onto each of them. I imagine if you were doing this to, like, make your HTML smaller, you’d have one big super-duper CSS selector like

cooltag-a, cooltag-b, cooltag-c, cooltag-🇩 {
    display: block;
}

or whatever, and you’d throw it wherever else the funny reset CSS sheet goes?^{[1] Link to footnote 1}

I cannot stress enough how much more readable this makes your HTML look. I have a spiffy little decorative sidebar on this blog, and while getting that there would’ve involved wrapping enough <div> tags to make my eyes gloss over, I instead was able to do this:

a small screencap showing my tags, "section-wrapper", "section-right" and "section-left" — `-right` and `-left` are in reverse order because it feels illegal for the non-content thing to be above the content. anyways look look

This, just very obviously seems better? I know this will be the point where I would find out that it has some critical flaw that breaks everything, but, outside of it defaulting to inline,^{[2] Link to footnote 2}it just seems unambiguously easier for me to work with. This is so nice!

I highly recommend a reset CSS, not just for its intended reasons of making sure everyone sees the same shit, but because there’s a lot of CSS rules that can’t be turned on by default without breaking backwards compatibility, but are just objectively better.
Even if you don’t use the rest, seriously, put *,*::before,*::after {box-sizing: border-box} at the top of your CSS. Trust me. Return to article via footnote 1
…Or trying to use it over a semantic tag, but like, why even do that? I only mention this because, somehow, it’s come up more than once that this is a thing people do. Why would I use a custom tag instead of <article> when that’s already the exact way I’d want to describe that tag?
I’m going to assume that someone really wanted to do something haunted, and not think too much about it. <div> replacements only! Return to article via footnote 2