> A hover-based clock, such as the one in Jane Ori's CPU Hack, is fast and stable, but requires you to hold your mouse on the screen, which some people claim does not count as turing complete for whatever reason, so I wanted this demo to be fully functional with zero user input.
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.
I wasn't sure whether to address the disconnect in the FAQ - I wanted it to be short and readable.
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.
I don't think it's that unrelated. If you make a system way more complex than it should be (clearly the case with CSS) it's obvious the risk of vulnerabilities increases exponentially.
Can an argument be bade that CSS only exists becuase javascript failed to develop a styling component to displace it?
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.
The complex parts of JavaScript are the semantics, not the syntax. You could reasonably easily spec a bytecode for JS to get rid of the syntax part, but nothing would change in the complexity (almost all modern engines parse to bytecode as the first step and operate on bytecode from then on).
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.
> CSS only exists becuase javascript failed to develop a styling component to displace it
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.
The instruction matrix they provide only includes 8086 instructions, not 186, 286 etc, which are all x86, hence the x at the start. From that wikipedia article, "The term "x86" came into being because the names of several successors to Intel's 8086 processor end in "86", including the 80186, 80286, 80386 and 80486. Colloquially, their names were "186", "286", "386" and "486"."
They write both. They write x86 repeatedly in the article and title, then show an instruction matrix that doesn't include, for example, the 468 CMPXCHG instructions or the crypto extensions PCLMULHQHQDQ instruction. Best I can guess, they mean 8086, which they think is equivalent to x86
Why is the 8086 not equivalent to x86? PCLMULHQHQDQ is from the CLMUL extension, which only began appearing in CPUs in the early 2010s - are CPUs from before then not x86?
x86 is an overarching group. Each processor is backwards compatible, I believe, so a 486 can run 8086 code, but they are not equivalent. If I download an x86 version of a program, I don't expect it to be written only in 8086 instructions
When you download an x86 program you're making a lot of other assumptions too, such as what the target operating system and hardware are. Even 8086 MSDOS software won't directly work in this emulator because it's not emulating DOS nor an IBM compatible, it has it's own addresses for the I/O. It's still x86 though.
Don't look at the end destination, look at the journey to the destination
* 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.
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...
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
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.
[0]: https://caniuse.com/wf-function
https://wpt.fyi/interop-2026
https://en.wikipedia.org/wiki/X86
They did write 8086 in the text, but x86 in the title.
Also: wow.
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.
(I swear at some point my brain will run out of space because it’s full of useless things like this.)
* 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.