* Learn low-level details of a basic but real-world CPU
* Practice the brain gymnastic of programming an atypical Turing-complete computer
Your created new connections in your brain, put to use some of the old established connections. Having a machine spit-out the emulator would rob you of all that. Like, you can drive from A to B, but running for A to B can do you much good.
That hover clock post is from 2023 and the "some people claim does not count" post is 2022. They were probably talking about the ones that make you check thousands of boxes to drive the logic forward.
Anyway, very cool advancement.
The idea is that, since a long time ago, there has always been demos that prove turing completeness and other programmy qualities in CSS, but that which people dismiss as requiring user inputs. The ones around by the time the comment got made were definitely at the "keep on clicking on the same spot on the screen" level - essentially just providing a clock.
And seeing discussion from after Jane Ori's hack, many still claim that even as much as hovering your mouse on a specific part of the screen makes css not a programming language.
"providing a clock" is not something to dismiss though. Arithmetic plus looping will give you a Turing machine, so you do need both or you're just showing the ability to do arithmetic.
And a proper Turing machine doesn't need an extra line of template html for each iteration. It's much easier to forgive finite memory, since a small amount of memory can go for billions of years while an iteration limit runs out fast.
This one passes all the bars, but I do think the bars were overall legitimate.
> many still claim that even as much as hovering your mouse on a specific part of the screen makes css not a programming language.
That bar is pretty silly.
It doesn't take much to be Turing-complete - if a system provides unbounded read/write memory plus branching or conditional recursion you're usually there.
As an example, Magic The Gathering (the card game) is Turing-complete: https://arxiv.org/abs/1904.09828 . You can use creature tokens as memory and various game mechanics to do flow control. Was this intentional by the designers? Most likely not...
* PowerPoint (Without Macros): using On-Click Animations and Hyperlinks, shapes on slides act as the tape and clicking them triggers animations that move the head or change the state of the slide.
* find and mkdir (Linux Commands): find has a -execdir flag executes commands for directories it finds. By using mkdir to create specific folder structures, you can create a feedback loop that functions as a Tag System (aka universal computation).
* Soldier Crabs: Researchers showed that swarms of Mictyris guinotae can be funneled through gates to implement Boolean logic. While a full computer hasn't been built with them, the logic gates (AND, OR, NOT) are the building blocks for one.
Even water is Turing Complete:
* Fluidic Logic Gates: the Coandă effect is the tendency of a fluid jet to stay attached to a convex surface. By using tiny air or water jets to push a main stream from one channel to another, you can create the fluid equivalent of a transistor.
* MONIAC (Monetary National Income Analogue Computer)
* Navier-Stokes equations describe how fluids move are TC.
* In 2015, Stanford researchers developed a computer that operates using the physics of moving water droplets. Tiny iron-infused water droplets moved by magnetic fields through a maze of tracks. The presence or absence of a droplet represents a 1 or a 0. By colliding or diverting each other, the droplets interact perform calculations.
Greenspun's 10th law.
I like to think webassembly is the right track. But ECMAScript and CSS alike need(ed) to devolve into a simpler byte-code like intermediary language syntax.
Browsers supporting complex languages has always been a bad idea, what they need to support is capabilities, and access and security primitives. wasm hasn't displaced javascript, because afaik, the wasm spec for browsers doesn't require them to implement javascript (and ideally, CSS) via wasm.
Instead of distilling, simplifying and speccing CSS and Javascript, browsers caked on layers upon layers of complicated features. The idea that browsers should define and regulate the languages developers use to write front-end code needs to die.
If you wanted to implement JS in wasm, you'd either need a bunch of wasm extensions for JS semantics (dynamic object shape, prototypal inheritance, etc), or you'd need to implement them in wasm from scratch and basically ship a JS runtime written in wasm. Either that, or you need to change the language, which means de facto adding a new language since the old JS still has to stick around for old pages.
there is no sortage of projects that do it (especially during the react era, people wanted to get rid of both html and css) but they get pushed down by dogma/inertia mostly. There was iOS constraint layout language ported to js. Seemed pretty cool, but the guy behind it decided to give up and everyone was like welp we tried, didn't work.
Completely unrelated but somehow unsurprising:
Zero-day CSS: CVE-2026-2441 exists in the wild - https://news.ycombinator.com/item?id=47062748 - February 2026 (233 comments)
[0] https://chromereleases.googleblog.com/2025/06/stable-channel...
I see CSS random() is only supported by Safari, I wonder if there's some side channel that would work in Chrome specifically? (I guess timing the user input would work)
The easiest way is to make an @property that's animated at ridiculous speeds that can be sampled to get (sort of) random bits.
Or wait for us to launch random() :-) (It's in development, available if you enable a flag)
The other week I had a fun project to implement IPv6 support in TempleOS. I did stop to think whether I should, and determined that absolutely not.
I asked Claude to start planning on doing it. It started referencing ZealOS, which is a fork of TempleOS and already has a functioning TCP stack.
That's when I determined that it would no longer even be fun, because someone else had already done all the heavy lifting, and gave up.
CSS should NOT be becoming turing complete. Nor any other DSL.
Hasn't it been so for a while? I mean I agree with you but it's a bit late
https://github.com/SLaks/Silon
Linked from here:
https://gwern.net/turing-complete#surprisingly-turing-comple...
I'm curious to know what you would rate as the most important features to make this work? It seems like calc+if do a lot of the heavy lifting, but the new function syntax is what makes instruction lookup tractable.
Also: wow.
I get the feeling some people just hate the web.
And CSS being Turing complete doesn't make it suitable to replace any JS it couldn't already replace, so why can't JS-haters dislike the idea? If I didn't like a language and people offered an even worse to use replacement I'd be justified in having distaste for it!
The features which are being exploited to implement this are indeed advances.
> If I didn't like a language and people offered an even worse to use replacement I'd be justified in having distaste for it!
You’re missing my point. Nobody is actually suggesting replacing JS with CSS, but many new CSS features eliminate the need to use JS to accomplish what you need in terms of behavior or style. Nobody is seriously suggesting CSS is a _replacement_ for JS, it’s just a better solution for certain common things on the web.
Saying this is an "x86 CPU emulator" is misleading, even if technically an 8086 is an example of the x86 family. To avoid the misleading ambiguity you'd have to say something like "emulates a member of the x86 family", at which point you may as well just say "8086 emulator".
They did write 8086 in the text, but x86 in the title.
Can it mine bitcoins or run worms?
Sorry to see internet regressing to Internet Explorer days.
Edited to add: This is the message I get when using Firefox.
It was popular on Mac Os (classic and X). It was also released for Solaris and HP-UX.
The specific way it became Turing complete seems more accidental than anything. We could have had pretty much the same features without the same --var handling.
> You’re missing my point. Nobody is actually suggesting replacing JS with CSS, but many new CSS features eliminate the need to use JS to accomplish what you need in terms of behavior or style.
I'm also talking about replacing specific things. But none of the specific things done in this article are easier in CSS than in JS.
If you're talking about different posts about CSS, I haven't seen those ones.
I don't think calling it x86 is misleading, and this is coming from the perspective of someone who dabbles in rev and pwn of x86.
and requiring a clock is imo dismissable, because pretty much all modern technology needs a clock too (either from the power grid, or from a hardware component designed for it)
As a tangent though, the system is already powered, you shouldn't need a secondary power source to make your Turing machine go. Something there still feels incomplete, like it probably passes but with an asterisk. But that distinction doesn't matter for CSS since it can self-clock.
(I swear at some point my brain will run out of space because it’s full of useless things like this.)
Relates to some Safari and Firefox engineers warning on pretty much every new CSS proposal to consider how it can be (ab)used for tracking.
I think the issue with CSS was that the low level APIs wasn't exposed which was the point of project Houdini https://developer.mozilla.org/en-US/docs/Web/API/Houdini_API...
Which is why these days it's easier in many cases to just embed an Arm core and implement your controller's functionality in software.
It's also easy to stumble into Turing completeness when you're just trying to let one setting modify another setting in a basic way.
My understanding was that things like DOM manipulation APIs would need to be (and are) exposed to the WASM runtime so that the JS-to-WASM compiler could do all the right bytecode "linking".
My idea is that if JS itself was require to in WASM, and native JS support didn't exist, the complexity in browsers would be reduced dramatically. And developers will be free to use different languages. Browsers will focus on APIs instead of language semantics. no more V8!
10-20 years from now, is it really ok to be stuck with JS and CSS? The complexity is compounding, ever newer webapi's get encoded as JS APIs, and the dependency mess will only increase. Browsers are about as complex in some ways as an operating system. If we think about the world in terms of decades, what is the plan? This is a very serious issue, because of how much the world depends on browser tech, and effectively, Google is the arbiter and overseer of that technology. I don't think this will work out well, unless there is some timely foresight in the architecture.