- You people totally overwhelmed my website... I use(d) Firebase static hosting because it's completely free and super simple, which reached the 10 GB monthly limit now. I changed to Cloudflare in the meantime, but it'll need some time for the DNS records to update. IN THE MEANTIME, PLEASE USE THE GITHUB PAGES LINK INSTEAD: https://benjaminaster.github.io/CSS-Minecraft/
- I made this almost three years ago now, to try out the limits of what's possible with pure CSS, and to test out the then-new CSS :has() selector.
- This project never got much traction until now, so I never bothered to write about how it works. Simon Willison now already wrote a blog post about it, so I guess I don't have to anymore... https://simonwillison.net/2025/May/26/css-minecraft/
- For the best experience, please view this on a desktop browser, either Chromium-based or Firefox.
- The source code is at https://github.com/BenjaminAster/CSS-Minecraft. The "index.pug" and "main.scss" files contain the actual source code; the rest is mostly just the compiled output.
Incredible. I was so skeptical that I went in on the neckruff and from there to a lacetop, it's really all generated based on background-image but without using images but gradients of specific colors, as well as box-shadows and the like.
ryukoposting · 1d ago
Wow, Dark Reader absolutely mutilated her.
lelandfe · 1d ago
Wow, mobile Safari hates this. Zooming in and scrolling around crashes the page constantly.
reaperducer · 1d ago
Works fine on my iPhone 14.
lelandfe · 1d ago
Similar problems on my MBP, actually – just sans crashed tab. Zooming in and scrolling around on Chrome and Safari cause the divs to rerender (repaint?) and often not all of them even do! E.g. Chrome: https://imgur.com/a/VWCAL9G
Scrolling is fine in Firefox but extremely slow.
yonatan8070 · 1d ago
It surprisingly smooth on Firefox on my Pixel 8
asimovDev · 1d ago
Interesting. Worked fine on my MBP in Safari. Even browsed around in the dev tools to see the styles used
Got this bookmarked to click around for inspiration in my free time.
Waterluvian · 1d ago
So many of these look deliciously interactive but aren’t. Is that because I’m on mobile or do they not do anything?
gs17 · 1d ago
I don't think any on the first page are interactive. There might be a few on the next page of it (I only found one where a pen changes color on hover).
matrix2596 · 1d ago
poring over it or pouring your attention :)
globie · 23h ago
My bad, I forgot I'm a liquid. It's too late to edit, but s/po\w*/poured over/ anyway :)
shultays · 1d ago
but they are all individual divs
simonw · 1d ago
This is fiendishly clever, and really quite elegant.
This is how CSS CAPTCHAs are made (for Tor websites), and sign up / login modals, and many other stuff.
cmrx64 · 1d ago
good write up, thanks. talk about a combinatorial explosion!
assimpleaspossi · 1d ago
But highly impractical and far beyond what CSS should be used for.
sd9 · 1d ago
Obviously...
That's why it was done
For fun and to see whether it could be done
assimpleaspossi · 1d ago
My point is that there will be too many who will look at this and start using CSS in ways it is not intended. Even today, far too many people attempt to use CSS for things best left for SVG.
dymk · 2h ago
This is basically the same take as "violent videogames cause school shootings"
johnisgood · 22h ago
CSS Minecraft, or CSS CAPTCHAs, or sign up / login modals cannot be done via SVG. This is needed for JS-less websites (e.g. Tor). CSS with HTML is perfect for this use-case.
spookie · 22h ago
If anything these tricks enable people to build stuff without JS.
I'm still here waiting for someone at W3C to get their stuff together and provide a spec for something that could enable an accessible hamburger menu with plain HTML + CSS.
Or a sane details element that DOES NOT REQUIRE JS TO CHANGE STATE (without interaction). Jesus.
hluska · 23h ago
These sorts of CSS experiments have been around for as long as CSS. There even used to be a site where an entire community would take basic markup and use CSS to turn it into something else.
(I just googled that phrase - the site is CSS Zen Garden. It’s impressive Google found it because that was a bad search.)
Some people did create monstrosities, others learned the limits of CSS and used that knowledge to advance CSS. So my point is that I believe in the ability of people to advance through discovering all the things they shouldn’t do.
assimpleaspossi · 5h ago
CSS Zen Garden is not an experiment as shown in the title of this post. The Garden shows how CSS can style the HTML elements in many different ways but it is not there to create or manipulate images as shown in the subject of this post.
That said, I have not looked at the Garden in many years so if you fine one, then you found .... one ... and I loop back to my original comment: that such things are impractical, it's not what CSS is for, and should be avoided.
Did anyone else involuntarily let out multiple expletives when they saw it and it dawned on them how hard this must have been?
This is insane to me.
skulk · 1d ago
If anyone's wondering how it manages the state, a quick peek into the source code shows that it uses radiobuttons and the HTML contains all the blocks you could ever possibly place.
johnh-hn · 1d ago
If anyone is equally curious how the camera state works, it looks like the camera is controlled by running animations when a button is in its :active state and pausing them otherwise.
globie · 1d ago
I... you're right. I was wondering why the world was only 9x9x9, there's 46k lines showing each block can have air, stone, grass, dirt, log, wood, leaves, or glass.
I kind of like it.
donatj · 1d ago
Radio buttons and checkboxes really are magic when it comes to doing neat things in pure CSS. We used to have a lot of neat stuff like pure html/css tabs and toggles but they didn't pass an accessibility audit.
90s_dev · 1d ago
That is the most hacky solution I may have ever seen in a CSS demo. I love it.
movedx01 · 1d ago
It's always radio buttons, every single time
avestura · 1d ago
Another hug of death. The website says "It must be upgraded via the Firebase console before it can begin serving traffic again."
Makes you wonder, how many webpages are dependant on such services. The Web has always been brittle, but it's a little sad seeing a website not able to survive ~50k users on its first day online.
Even the least offenders, GitHub Pages, broke links before [0].
It's absolutely brilliant how rotation and movement control is achieved by changing the animation-play-state value using the :active pseudo-class on button elements.
Truly incredible from an HTML perspective, but I think also a testament to how catchy and simple Minecraft is as a concept... a few minutes of noodling around in here and I already built myself a cute little tree and a hill: https://i.imgur.com/PjlDWo5.png
patates · 1d ago
Just think about setting what Minecraft has achieved as requirements from the get go: 1) Be one of the most successful games ever created. 2) Basic game mechanics should be possible to be implemented via just HTML and CSS (no JS).
I really like doing this when something extraordinary happens by "accident".
bradly · 1d ago
Very impressive!
As I've hit my mid-life slide and (regressed|progressed) back to my youth-self, I've found myself just writing a bunch of apps and sites in html and css and really enjoying it.
One thing I still would like to see cracked is a random-like number in pure CSS. You can almost us there with some of the math functions and browser attributes, but I haven't found anything reliable.
Unfortunately that solution does not work on Firefox or Safari.
menzoic · 1d ago
Can LLMs help?
Cthulhu_ · 1d ago
Can they? I think it's weird that you ask a question (or, offer a possible solution in the shape of a question) without verifying your own assertion first.
To answer your question, LLMs confirm you can't generate a random number in CSS.
reverendsteveii · 1d ago
alas, it seems that just shouting "AI" at problems is the latest trend in people who don't build software acting as though they know how building software works.
It's sometimes done to make the same markup compatible with XHTML, without harming its interpretation in HTML.
assimpleaspossi · 1d ago
You are either running XHTML or you are not. No need to carry any compatibility overhead. I doubt he is serving XHTML.
ThunderSizzle · 1d ago
I personally prefer <input /> if only to stop other developers to not try doing <input>content </input>.
pests · 1d ago
There are other tags you can omit the closing tag but yet the opening tag shouldn’t be self-closed.
<ol>
<li>one
<li>two
</ol>
I think even the final closing ol can be omitted as there are rules to auto close elements when encountering tags that don’t make sense in context.
ThunderSizzle · 1d ago
I know that, but many developers don't. I can't wait to see the confusion on why my tag didn't auto-close like a <li> tag.
Ambiguity can be a dangerous thing, and not closing HTML tags can be a cause of that in my experience.
assimpleaspossi · 1d ago
The term for such "other developers" is "hobbyists".
There are other terms but I won't list them here.
ThunderSizzle · 1d ago
Sometimes "other developers" is also "coworkers".
I've found less ambiguity to be a better thing than not, where possible. Self-closing a tag that can't contain anything is one such example of removing ambiguity for "hobbyists".
assimpleaspossi · 19h ago
One would need to know the tag is self-closing in order to put the closing slash in. Right? So if one knows it's self-closing already, why do they need to add the extra weight?
Makes no sense.
If one wants to add content to a self-closing element, one has far more problems than we're talking about here.
ThunderSizzle · 17h ago
> If one wants to add content to a self-closing element, one has far more problems than we're talking about here.
Yes.
taosx · 1d ago
Blew my mind. I have hundreds of tabs open, no issue on linux chrome.
echoangle · 1d ago
I think at some point the number of tabs doesn't matter because the tab is unloaded and the state is maybe stored on disk. As long as you don't open them, having them open shouldn't slow the browser down.
Damn, just visiting this site makes me want to reinstall Minecraft haha.
secondbrain_io · 1d ago
I also got "Bandwidth Quota Exceeded". Seems like you're doing well!
ddtaylor · 1d ago
I remember discovering this trick nearly two decades ago. A co-worker and myself were a bit puzzled at the time and we kind of tossed the idea in the air that "doesn't this mean CSS is Turing Complete?" but we moved on to making things work on IE6 for old clients.
voodooEntity · 1d ago
Very nice work :) especially that you even support building sideways and the "hover" always is perfectly placed. Thats something that amazes me the most how clean it feels to place a block. Very good job!
perdomon · 1d ago
My one regret in life is not having seen this before your Firebase credits were spent for the month. Looking forward to a June attempt!
Recently I came across Quake implemented within a single WebGL shader (https://www.shadertoy.com/view/lsKfWd), but this is another level. HTML/CSS is a programming language now.
teddyh · 1d ago
It’s extremely impressive, but it’s not “Quake”; it’s only the difficulty selection hallway from Quake. No enemies.
cod3rboy · 1d ago
This is breathtaking and embodiment of creativity.
Truly a legend!
justinde · 1d ago
Web-based minecraft, when?
fenomas · 1d ago
Only guessing, but I have a theory that Mojang considered that circa 2017 :D
In 2019 they released a web version of minecraft classic, as a quirky marketing thing for the game's anniversary. But what they released turned out to be built on my open-source voxel engine, and when I dug around their code I realized they'd yoinked my engine a solid two years earlier.
And the demo they released was probably not two year's of work, so my theory is that somebody at Mojang investigated the idea of minecraft-but-JS, and made a demo but then decided not to pursue it, and then later on it got recycled for the marketing demo. (which, annoyingly for me, they pretended was an old alpha build of Minecraft instead of a new thing built on open source.)
The demo is still live, though the multiplayer stopped working the same day it launched:
Humorous postscript, btw: two months after Mojang forked my voxel engine, somebody left an anonymous "this is awful, you are a terrible programmer" comment on the engine repo.
It's probably a total coincidence, but I like to imagine that the comment came from somebody at Mojang, and that my awful code is the reason why minecraft isn't a web app today :D
BtM909 · 1d ago
Is your repo still available?
fenomas · 1d ago
Yup! Though I haven't touched it in several years:
I was confused because I thought Minecraft was originally Java, but that is Javascript. Wikipedia explains:
>On 7 May, 2019, coinciding with Minecraft's 10th anniversary, a JavaScript recreation of an old 2009 Java Edition build named Minecraft Classic was made available to play online for free.
Wow! I had no idea, it even supports up to 9 additional players.
charcircuit · 1d ago
The full game was available on minecraft.net for many years. At times it was the only way to play multiplayer when the authentication server would go down.
beeflet · 1d ago
The full java version of the game was ported to webassembly/webgl a while ago. It's called eaglercraft: https://eaglercraft.com
zimpenfish · 1d ago
Minor nit - "the full java version of an at-least 8 years old release" (which is necessarily missing -a lot- of what people would consider "Minecraft" these days.)
immibis · 1d ago
Minecraft these days is missing a lot of what people would consider "Minecraft" 8 years ago.
sparky_ · 1d ago
I don't get it - isn't this blatant copyright infringement? Seems like they're just running some kind of cracked Minecraft build with a JVM-in-JS layer or some such trickery?
beeflet · 1d ago
yeah, it's JVM-to-wasm plus an lwjgl-to-webgl library plus various compression packed into a single .html file
auxiliarymoose · 1d ago
The phone is ringing—Java Applets called B-)
thrance · 1d ago
Fun fact: one of the first versions of Minecraft (the "classic" one) was playable in a web browser. I actually did play it as a young teen and later thought I must have dreamt it, when I couldn't find it anywhere.
rbits · 1d ago
Yeah I remember that. I think it was back in version 1.6 or something. It kinda blew my mind as a kid playing a full-on computer game in a browser.
Pretty slick! I never had played minecraft before. I never knew how blocks were place down until I ran this page. But it needs to be able to use the mouse to rotate, and mouse-wheel to scale!
terribleperson · 1d ago
When playing the actual game, your viewpoint moves with the character, moved by the WASD keys and oriented with the mouse. You can only ever place one block at a time, though.
bpiroman · 1d ago
that's amazing!!!
zizomod · 1d ago
That's crazy
ryanisnan · 1d ago
Well done!
est · 1d ago
I wonder when AIs can write clever codes like this. Given a surprising constraint.
johnisgood · 1d ago
About a year ago I tried to make GPT give me a CAPTCHA using the same method and it failed (even after helping it quite a lot). I don't know how it would fare now. You can find a CAPTCHA like this in use for the Tor variant of Reddit (?).
90s_dev · 1d ago
> For the best performance, please close other tabs and running programs.
This has always been the case with CSS, hasn't it? When you use it for rendering something relatively complex, you're kinda doomed.
I get the dream, we want everything to be declarative, and leave room for future optimizations, so that we can write once and run everywhere forever.
But in practice, it's not really an improvement over traditional GUIs that let you draw directly. Hence CSS is literally adding draw[1].
This is a huge reason 90s.dev doesn't use HTML/CSS but starts from scratch and lets you draw right into WebGL2 yourself, or with high-level APIs if you want.
> When you use it for rendering something relatively complex, you're kinda doomed.
Can you describe a time that happened to you, and why you felt doomed?
That doesn’t like something that a person who has really used CSS in any meaningful way would say. Sharp edges, sure, but what technology doesn’t have that?
None4U · 1d ago
The game https://corru.observer/ is a great example of a CSS-rendered 3D video game that runs fairly well on modern devices (even playable on mobile although it'll try to block you based on viewport size if you're not in "desktop mode")
Some comments on this from my side:
- You people totally overwhelmed my website... I use(d) Firebase static hosting because it's completely free and super simple, which reached the 10 GB monthly limit now. I changed to Cloudflare in the meantime, but it'll need some time for the DNS records to update. IN THE MEANTIME, PLEASE USE THE GITHUB PAGES LINK INSTEAD: https://benjaminaster.github.io/CSS-Minecraft/
- I made this almost three years ago now, to try out the limits of what's possible with pure CSS, and to test out the then-new CSS :has() selector.
- This project never got much traction until now, so I never bothered to write about how it works. Simon Willison now already wrote a blog post about it, so I guess I don't have to anymore... https://simonwillison.net/2025/May/26/css-minecraft/
- For the best experience, please view this on a desktop browser, either Chromium-based or Firefox.
- The source code is at https://github.com/BenjaminAster/CSS-Minecraft. The "index.pug" and "main.scss" files contain the actual source code; the rest is mostly just the compiled output.
- Here is a video of me building a house with it: https://www.youtube.com/watch?v=OH8-Y9frP5k
This immediately brought "A Single Div"[0] to mind, which stood as the coolest CSS demo I'd seen for... 11 years!
This one takes the cake. I'll be pouring over it. Thanks!
[0]: https://a.singlediv.com/
Scrolling is fine in Firefox but extremely slow.
https://lynnandtonic.com/work/
Also love seeing Phoenix devs mentioned!
https://lynnandtonic.com/archive/
Got this bookmarked to click around for inspiration in my free time.
I made some of my own notes on how this works here: https://simonwillison.net/2025/May/26/css-minecraft/
That's why it was done
For fun and to see whether it could be done
I'm still here waiting for someone at W3C to get their stuff together and provide a spec for something that could enable an accessible hamburger menu with plain HTML + CSS.
Or a sane details element that DOES NOT REQUIRE JS TO CHANGE STATE (without interaction). Jesus.
(I just googled that phrase - the site is CSS Zen Garden. It’s impressive Google found it because that was a bad search.)
Some people did create monstrosities, others learned the limits of CSS and used that knowledge to advance CSS. So my point is that I believe in the ability of people to advance through discovering all the things they shouldn’t do.
That said, I have not looked at the Garden in many years so if you fine one, then you found .... one ... and I loop back to my original comment: that such things are impractical, it's not what CSS is for, and should be avoided.
This is insane to me.
I kind of like it.
Wayback machine for when it used to work: https://web.archive.org/web/20250317122419/https://benjamina...
Even the least offenders, GitHub Pages, broke links before [0].
[0]: https://github.blog/news-insights/product-news/new-github-pa...
https://news.ycombinator.com/item?id=33579407
https://keithclark.co.uk/labs/css-fps/desktop/
https://keithclark.co.uk/labs/css-3d-shadows/
https://github.com/BenjaminAster/CSS-Minecraft/blob/main/mai...
I really like doing this when something extraordinary happens by "accident".
As I've hit my mid-life slide and (regressed|progressed) back to my youth-self, I've found myself just writing a bunch of apps and sites in html and css and really enjoying it.
One thing I still would like to see cracked is a random-like number in pure CSS. You can almost us there with some of the math functions and browser attributes, but I haven't found anything reliable.
To answer your question, LLMs confirm you can't generate a random number in CSS.
https://web.archive.org/web/20250317122419/https://benjamina...
Concatenating strings is not that complicated.
... and 46,022 lines of HTML (3.07MB)
It implements voxels via <input type="radio" />.
Each of the faces of each voxel is configured via <label>s, one for each face having a different CSS class.
There is a voxel for each type of block (dirt, grass, stone, etc) and only one is activated at a time.
The <input>s are arranged in a 9x9 grid 10 blocks tall times the number of different types of blocks (about 6500 total).
All that is enclosed with <div>s with CSS classes that respond to the camera navigation (look up/down, move up/down, forward/back, clockwise/counter)
That is brilliant!
https://html.spec.whatwg.org/dev/input.html#the-input-elemen...
Ambiguity can be a dangerous thing, and not closing HTML tags can be a cause of that in my experience.
There are other terms but I won't list them here.
I've found less ambiguity to be a better thing than not, where possible. Self-closing a tag that can't contain anything is one such example of removing ambiguity for "hobbyists".
Makes no sense.
If one wants to add content to a self-closing element, one has far more problems than we're talking about here.
Yes.
In 2019 they released a web version of minecraft classic, as a quirky marketing thing for the game's anniversary. But what they released turned out to be built on my open-source voxel engine, and when I dug around their code I realized they'd yoinked my engine a solid two years earlier.
And the demo they released was probably not two year's of work, so my theory is that somebody at Mojang investigated the idea of minecraft-but-JS, and made a demo but then decided not to pursue it, and then later on it got recycled for the marketing demo. (which, annoyingly for me, they pretended was an old alpha build of Minecraft instead of a new thing built on open source.)
The demo is still live, though the multiplayer stopped working the same day it launched:
https://classic.minecraft.net/
It's probably a total coincidence, but I like to imagine that the comment came from somebody at Mojang, and that my awful code is the reason why minecraft isn't a web app today :D
https://github.com/fenomas/noa
>On 7 May, 2019, coinciding with Minecraft's 10th anniversary, a JavaScript recreation of an old 2009 Java Edition build named Minecraft Classic was made available to play online for free.
https://en.wikipedia.org/wiki/Minecraft
No comments yet
This has always been the case with CSS, hasn't it? When you use it for rendering something relatively complex, you're kinda doomed.
I get the dream, we want everything to be declarative, and leave room for future optimizations, so that we can write once and run everywhere forever.
But in practice, it's not really an improvement over traditional GUIs that let you draw directly. Hence CSS is literally adding draw[1].
This is a huge reason 90s.dev doesn't use HTML/CSS but starts from scratch and lets you draw right into WebGL2 yourself, or with high-level APIs if you want.
[1] https://developer.mozilla.org/en-US/docs/Web/API/CSS_Paintin...
Can you describe a time that happened to you, and why you felt doomed?
That doesn’t like something that a person who has really used CSS in any meaningful way would say. Sharp edges, sure, but what technology doesn’t have that?