Today’s world requires us to make complex and nuanced decisions about our digital security. Evaluating when to use a secure messaging app like Signal or WhatsApp, which passwords to store on your smartphone, or what to share on social media requires us to assess risks and make judgments accordingly. Arriving at any conclusion is an exercise in threat modeling.

In security, threat modeling is the process of determining what security measures make sense in your particular situation. It’s a way to think about potential risks, possible defenses, and the costs of both. It’s how experts avoid being distracted by irrelevant risks or overburdened by undue costs.

We threat model all the time. We might decide to walk down one street instead of another, or use an internet VPN when browsing dubious sites. Perhaps we understand the risks in detail, but more likely we are relying on intuition or some trusted authority. But in the U.S. and elsewhere, the average person’s threat model is changing—specifically involving how we protect our personal information. Previously, most concern centered on corporate surveillance; companies like Google and Facebook engaging in digital surveillance to maximize their profit. Increasingly, however, many people are worried about government surveillance and how the government could weaponize personal data.

Since the beginning of this year, the Trump administration’s actions in this area have raised alarm bells: The Department of Government Efficiency (DOGE) took data from federal agencies, Palantir combined disparate streams of government data into a single system, and Immigration and Customs Enforcement (ICE) used social media posts as a reason to deny someone entry into the U.S.

These threats, and others posed by a techno-authoritarian regime, are vastly different from those presented by a corporate monopolistic regime—and different yet again in a society where both are working together. Contending with these new threats requires a different approach to personal digital devices, cloud services, social media, and data in general.

What Data Does the Government Already Have?

For years, most public attention has centered on the risks of tech companies gathering behavioral data. This is an enormous amount of data, generally used to predict and influence consumers’ future behavior—rather than as a means of uncovering our past. Although commercial data is highly intimate—such as knowledge of your precise location over the course of a year, or the contents of every Facebook post you have ever created—it’s not the same thing as tax returns, police records, unemployment insurance applications, or medical history.

The U.S. government holds extensive data about everyone living inside its borders, some of it very sensitive—and there’s not much that can be done about it. This information consists largely of facts that people are legally obligated to tell the government. The IRS has a lot of very sensitive data about personal finances. The Treasury Department has data about any money received from the government. The Office of Personnel Management has an enormous amount of detailed information about government employees—including the very personal form required to get a security clearance. The Census Bureau possesses vast data about everyone living in the U.S., including, for example, a database of real estate ownership in the country. The Department of Defense and the Bureau of Veterans Affairs have data about present and former members of the military, the Department of Homeland Security has travel information, and various agencies possess health records. And so on.

It is safe to assume that the government has—or will soon have—access to all of this government data. This sounds like a tautology, but in the past, the U.S. government largely followed the many laws limiting how those databases were used, especially regarding how they were shared, combined, and correlated. Under the second Trump administration, this no longer seems to be the case.

Augmenting Government Data with Corporate Data

The mechanisms of corporate surveillance haven’t gone away. Compute technology is constantly spying on its users—and that data is being used to influence us. Companies like Google and Meta are vast surveillance machines, and they use that data to fuel advertising. A smartphone is a portable surveillance device, constantly recording things like location and communication. Cars, and many other Internet of Things devices, do the same. Credit card companies, health insurers, internet retailers, and social media sites all have detailed data about you—and there is a vast industry that buys and sells this intimate data.

This isn’t news. What’s different in a techno-authoritarian regime is that this data is also shared with the government, either as a paid service or as demanded by local law. Amazon shares Ring doorbell data with the police. Flock, a company that collects license plate data from cars around the country, shares data with the police as well. And just as Chinese corporations share user data with the government and companies like Verizon shared calling records with the National Security Agency (NSA) after the Sept. 11 terrorist attacks, an authoritarian government will use this data as well.

Personal Targeting Using Data

The government has vast capabilities for targeted surveillance, both technically and legally. If a high-level figure is targeted by name, it is almost certain that the government can access their data. The government will use its investigatory powers to the fullest: It will go through government data, remotely hack phones and computers, spy on communications, and raid a home. It will compel third parties, like banks, cell providers, email providers, cloud storage services, and social media companies, to turn over data. To the extent those companies keep backups, the government will even be able to obtain deleted data.

This data can be used for prosecution—possibly selectively. This has been made evident in recent weeks, as the Trump administration personally targeted perceived enemies for “mortgage fraud.” This was a clear example of weaponization of data. Given all the data the government requires people to divulge, there will be something there to prosecute.

Although alarming, this sort of targeted attack doesn’t scale. As vast as the government’s information is and as powerful as its capabilities are, they are not infinite. They can be deployed against only a limited number of people. And most people will never be that high on the priorities list.

The Risks of Mass Surveillance

Mass surveillance is surveillance without specific targets. For most people, this is where the primary risks lie. Even if we’re not targeted by name, personal data could raise red flags, drawing unwanted scrutiny.

The risks here are twofold. First, mass surveillance could be used to single out people to harass or arrest: when they cross the border, show up at immigration hearings, attend a protest, are stopped by the police for speeding, or just as they’re living their normal lives. Second, mass surveillance could be used to threaten or blackmail. In the first case, the government is using that database to find a plausible excuse for its actions. In the second, it is looking for an actual infraction that it could selectively prosecute—or not.

Mitigating these risks is difficult, because it would require not interacting with either the government or corporations in everyday life—and living in the woods without any electronics isn’t realistic for most of us. Additionally, this strategy protects only future information; it does nothing to protect the information generated in the past. That said, going back and scrubbing social media accounts and cloud storage does have some value. Whether it’s right for you depends on your personal situation.

Opportunistic Use of Data

Beyond data given to third parties—either corporations or the government—there is also data users keep in their possession.This data may be stored on personal devices such as computers and phones or, more likely today, in some cloud service and accessible from those devices. Here, the risks are different: Some authority could confiscate your device and look through it.

This is not just speculative. There are many stories of ICE agents examining people’s phones and computers when they attempt to enter the U.S.: their emails, contact lists, documents, photos, browser history, and social media posts.

There are several different defenses you can deploy, presented from least to most extreme. First, you can scrub devices of potentially incriminating information, either as a matter of course or before entering a higher-risk situation. Second, you could consider deleting—even temporarily—social media and other apps so that someone with access to a device doesn’t get access to those accounts—this includes your contacts list. If a phone is swept up in a government raid, your contacts become their next targets.

Third, you could choose not to carry your device with you at all, opting instead for a burner phone without contacts, email access, and accounts, or go electronics-free entirely. This may sound extreme—and getting it right is hard—but I know many people today who have stripped-down computers and sanitized phones for international travel. At the same time, there are also stories of people being denied entry to the U.S. because they are carrying what is obviously a burner phone—or no phone at all.

Encryption Isn’t a Magic Bullet—But Use It Anyway

Encryption protects your data while it’s not being used, and your devices when they’re turned off. This doesn’t help if a border agent forces you to turn on your phone and computer. And it doesn’t protect metadata, which needs to be unencrypted for the system to function. This metadata can be extremely valuable. For example, Signal, WhatsApp, and iMessage all encrypt the contents of your text messages—the data—but information about who you are texting and when must remain unencrypted.

Also, if the NSA wants access to someone’s phone, it can get it. Encryption is no help against that sort of sophisticated targeted attack. But, again, most of us aren’t that important and even the NSA can target only so many people. What encryption safeguards against is mass surveillance.

I recommend Signal for text messages above all other apps. But if you are in a country where having Signal on a device is in itself incriminating, then use WhatsApp. Signal is better, but everyone has WhatsApp installed on their phones, so it doesn’t raise the same suspicion. Also, it’s a no-brainer to turn on your computer’s built-in encryption: BitLocker for Windows and FileVault for Macs.

On the subject of data and metadata, it’s worth noting that data poisoning doesn’t help nearly as much as you might think. That is, it doesn’t do much good to add hundreds of random strangers to an address book or bogus internet searches to a browser history to hide the real ones. Modern analysis tools can see through all of that.

Shifting Risks of Decentralization

This notion of individual targeting, and the inability of the government to do that at scale, starts to fail as the authoritarian system becomes more decentralized. After all, if repression comes from the top, it affects only senior government officials and people who people in power personally dislike. If it comes from the bottom, it affects everybody. But decentralization looks much like the events playing out with ICE harassing, detaining, and disappearing people—everyone has to fear it.

This can go much further. Imagine there is a government official assigned to your neighborhood, or your block, or your apartment building. It’s worth that person’s time to scrutinize everybody’s social media posts, email, and chat logs. For anyone in that situation, limiting what you do online is the only defense.

Being Innocent Won’t Protect You

This is vital to understand. Surveillance systems and sorting algorithms make mistakes. This is apparent in the fact that we are routinely served advertisements for products that don’t interest us at all. Those mistakes are relatively harmless—who cares about a poorly targeted ad?—but a similar mistake at an immigration hearing can get someone deported.

An authoritarian government doesn’t care. Mistakes are a feature and not a bug of authoritarian surveillance. If ICE targets only people it can go after legally, then everyone knows whether or not they need to fear ICE. If ICE occasionally makes mistakes by arresting Americans and deporting innocents, then everyone has to fear it. This is by design.

Effective Opposition Requires Being Online

For most people, phones are an essential part of daily life. If you leave yours at home when you attend a protest, you won’t be able to film police violence. Or coordinate with your friends and figure out where to meet. Or use a navigation app to get to the protest in the first place.

Threat modeling is all about trade-offs. Understanding yours depends not only on the technology and its capabilities but also on your personal goals. Are you trying to keep your head down and survive—or get out? Are you wanting to protest legally? Are you doing more, maybe throwing sand into the gears of an authoritarian government, or even engaging in active resistance? The more you are doing, the more technology you need—and the more technology will be used against you. There are no simple answers, only choices.

For the first time since it launched 36 years ago, the iconic Casio F-91W digital watch is getting some smart upgrades — but not from Casio. The Ollee Watch One is a replacement mainboard for the Casio F-91W, A158W, and several other watch models that can be installed without the need for a soldering iron or any electronics know-how aside from being able to remove a few screws and clips. It doesn’t upgrade Casio’s timepieces to the point where they’re on-par with the Apple Watch, but it does add Bluetooth and app connectivity so the watch can set the time automatically, track step counts, play games, and be more personalized using an improved color-changing backlight.

The DIY version of the Ollee Watch one, which requires you to already have one of six different supported Casio watch models (including the F-84W, A159W, A171W, and W-59) is available now for $54.99. If you’re not confident in tackling the upgrade yourself, which appears to take around six minutes, the company also sells the Casio F-91W-1 and A158W-1 preinstalled with the upgrade for $99.99, but it’s currently sold out.

The upgraded mainboard includes an accelerometer for step counting and  an upgraded audio buzzer that will alert you when you’ve reached a goal you set using an accompanying iOS and Android mobile app. The upgrade also adds a temperature sensor, an improved LED backlight that lets you adjust the color or use your watch as a flashlight, world time functionality, and the option to create five timer presets.

There’s no notifications, and while the Ollie Watch One does include alternate watch faces, it doesn’t upgrade the basic segmented screen that Casio includes. That being said, even with those screen limitations you can play a simplified version of Blackjack or a game called Ping that has you controlling a paddle to keep a bouncing ball up in the air. Battery life isn’t quite as impressive as the seven years Casio claims for an unmodified F91W-1, but thanks to its use of Bluetooth low energy the upgrade kit only reduces battery life to about 10 months on a CR2016 battery.

It’s becoming somewhat of a running gag that any device or object will be made ‘smart’ these days, whether it’s a phone, TV, refrigerator, home thermostat, headphones or glasses. This generally means somehow cramming a computer, display, camera and other components into the unsuspecting device, with the overarching goal of somehow making it more useful to the user and not impacting its basic functionality.

Although smart phones and smart TVs have been readily embraced, smart glasses have always been a bit of a tough sell. Part of the problem here is of course that most people do not generally wear glasses, between people whose vision does not require correction and those who wear e.g. contact lenses. This means that the market for smart glasses isn’t immediately obvious. Does it target people who wear glasses anyway, people who wear sunglasses a lot, or will this basically move a smart phone’s functionality to your face?

Smart glasses also raise many privacy concerns, as their cameras and microphones may be recording at any given time, which can be unnerving to people. When Google launched their Google Glass smart glasses, this led to the coining of the term ‘glasshole‘ for people who refuse to follow perceived proper smart glasses etiquette.

Defining Smart Glasses

Most smart glasses are shaped like rather chubby, often thick-rimmed glasses. This is to accommodate the miniaturized computer, battery and generally a bunch of cameras and microphones. Generally some kind of projection system is used to either project a translucent display on one of the glasses, or in more extreme cases a laser directly projects the image into your retina. The control interface can range from a smartphone app to touch controls, to the new ‘Neural Band’ wristband that’s part of Meta’s collaboration with Ray-Ban in a package that some might call rather dorky.

This particular device crams a 600 x 600 pixel color display into the right lens, along with six microphones and a 12 MP camera in addition to stereo speakers. Rather than an all-encompassing display or an augmented-reality experience, this is more of a display that you reportedly see floating when you glance somewhat to your right, taking up 20 degrees of said right eyepiece.

Perhaps most interesting is the neural band here, which uses electromyography (EMG) to detect the motion of muscles in your wrist by their electrical signals to determine the motion that you made with your arm and hand. Purportedly you’ll be able to type this way too, but this feature is currently ‘in beta’.

Slow March Of Progress

When we compare these Ray-Ban Display smart glasses to 2013’s Google Glass, when the Explorer Edition was made available in limited quantities to the public, it is undeniable that the processor guts in the Ray-Bans are more powerful, it’s got double the Flash storage, but the RAM is the same 2 GB, albeit faster LPRDDR4x. In terms of the display it’s slightly higher resolution and probably slightly better fidelity, but this still has to be tested.

Both have similar touch controls on the right side for basic control, with apparently the new wristband being the major innovation here. This just comes with the minor issue of now having to wear another wrist-mounted gadget that requires regular charging. If you are already someone who wears a smart watch or similar, then you better have some space on your other wrist to wear it.

One of the things that Google Glass and similar solutions have really struggled with – including Apple’s Vision AR gadget – is that of practical use cases. As cool as it can be to have a little head-mounted display that you can glance at surreptitiously, with nobody else around you being able to glance at the naughty cat pictures or personal emails currently being displayed, this never was a use case that convinced people into buying their own Google Glass device.

In the case of Meta’s smart glasses, they seem to bank on Meta AI integration, along with real-time captions for conversations in foreign languages. Awkward point here is of course that none of these features are impossible with a run-of-the-mill smartphone, and those can do even more, with a much larger display.

Ditto with the on-screen map navigation, which overlays a Meta Maps view akin to that of Google’s and Apple’s solutions to help you find your way. Although this might seem cool, you will still want to whip out your phone when you have to ask a friendly local when said route navigation feature inevitably goes sideways.

Amidst the scrambling for a raison d’être for smart glasses, it seems unlikely that society’s attitude towards ‘glassholes’ has changed either.

Welcome To The Panopticon

The idea behind the panopticon design, as created by Jeremy Bentham in the 18th century, is that a single person can keep an eye on a large number of individuals, all of whom cannot be certain that they are or are not being observed at that very moment. Although Bentham did not intent for it to be solely used with prisons and similar buildings, this is where it found the most uptake. Inspired by this design, we got more modern takes, such as the Telescreens in Orwell’s novel Nineteen-Eighty Four whose cameras are always on, but you can not be sure that someone is watching that particular screen.

In today’s modern era where cameras are basically everywhere, from CCTV cameras on and inside buildings, to doorbells and the personal surveillance devices we call ‘smartphones’, we also got areas where people are less appreciative of having cameras aimed on them. Unlike a smartphone where it’s rather obvious when someone is recording or taking photos, smart glasses aren’t necessarily that obvious. Although some do light up a LED or such, it’s easy to miss this sign.

In that article a TikTok video is described by a woman who was distraught to see that the person at the wax salon that she had an appointment at was wearing smart glasses. Unless you’re actively looking at and listening for the cues emitted by that particular brand of smart glasses, you may not know whether your waxing session isn’t being recorded in glorious full-HD or better for later sharing.

This is a concern that blew up during the years that Google Glass was being pushed by Google, and so far it doesn’t appear that people’s opinions on this have changed at all. Which makes it even more awkward when those smart glasses are your only prescription glasses that you have on you at the time. Do you still take them off when you enter a place where photography and filming is forbidden?

Dumber Smart Glasses

Although most of the focus in the media and elsewhere is on smart glasses like Google Glass and now Meta/Ray-Ban’s offerings, there are others too that fall under this umbrella term. Certain auto-darkening sunglasses are called ‘smart glasses’, while others are designed to act more like portable screens that are used with a laptop or other computer system. Then there are the augmented- and mixed-reality glasses, which come in a wide variety of forms and shapes. None of these are the camera-equipped types that we discussed here, of course, and thus do not carry the same stigma.

Whether Meta’s attempt where Google Glass failed will be more successful remains to be seen. If the criteria is that a ‘smart’ version of a device enhances it, then it’s hard to argue that a smart phone isn’t much more than just a cellular phone. At the same time the ‘why’ for cramming a screen and computer into a set of dorky glasses remains much harder to answer.

Feel free to sound off in the comments if you have a good use case for smart glasses. Ditto if you would totally purchase or have already purchased a version of the Ray-Ban Display smart glasses. Inquisitive minds would like to know whether this might be Google Glass’ redemption arch.

In 1968, Charlotte Rude and Hjördis Olsson-Une were two young graduates of Sweden's Konstfack University, where they had studied art and design. The two moved to Älmhult, Sweden, where a glassworks was located; having caught the material exploration bug at design school, the two wanted to experiment with glass.

The pair had very little money and shared an apartment. To furnish it, they bought inexpensive leftover particle board from a nearby construction site, and built pieces they designed themselves.

Älmhult was also where Ikea had opened their first store, back in 1958, and was where their headquarters were based. Some of Rude and Olsson-Une's neighbors worked for Ikea, and when they saw the designers' self-created furniture, encouraged them to try to sell the designs to Ikea. The neighbors introduced them to Ikea manager Gillis Lundgren.

Lundgren didn't buy their designs. Instead he offered them full-time jobs. The duo accepted, and soon began designing furniture.

In 1970s, the Ikea store in Stockholm suffered a fire and needed to be rebuilt. The brass decided they may as well add a large play area for children. The task of designing the play area fell to Rude and Olsson-Une, who were then Ikea's youngest designers. The two designed a sort of indoor playground filled with pillows, ropes and platforms.

But "the biggest star of the play area," according to Ikea, "was the ball pit."

The idea came when Charlotte and Hjördis were opening boxes containing a new type of protective packing material. It consisted of small plastic balls, and reminded Charlotte of the then wildly popular bean bags that kids would sit and lie down in.

They imagined how one could jump and swim around in a sea of balls if it was deep and wide enough. However, these balls were too small. Children might put them in their mouths and choke. At the time, plastic was growing fast as a material, and the young designers soon found lighter and bigger multicoloured balls to use.

A huge wooden box – deep enough to jump into – was built with particleboard and filled with thousands of balls. When the play area opened in 1971, the ball pit became a huge hit. Kids loved it, and families were soon rushing to IKEA to let their children try out the new invention. Later in the 1970s, ball pits of all sorts started popping up in everything from amusement parks to fast-food restaurants, but the ball pit in the Stockholm IKEA store in 1971 was likely the first one in the world.

Rude and Olsson-Une didn't stay at Ikea for long; after just five years, in 1973, they moved to Copenhagen to pursue graduate studies at the Royal Danish Academy of Fine Arts. They took on freelance design work--and apparently faded into obscurity. I can find no record of their work after their time at Ikea.

Observations of gravitational waves produced by 2 black holes colliding and merging have allowed scientists to confirm fundamental predictions made by Albert Einstein and Stephen Hawking about the nature of the universe.

“This is the clearest view yet of the nature of black holes,” says astrophysicist Maximiliano Isi, who co-led the analysis published in the Physical Review Letters.

Cataclysmic cosmological events, such as the merging of 2 black holes, distort the fabric of the universe. This sends out ripples, or ‘gravitational waves’, which stretch and contract space-time.

Gravitational waves produced by merging black holes were first detected by the US National Science Foundation Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2015. LIGO detects changes in space-time smaller than 1/10,000 the width of a proton. 

Today, it operates with international partners, the Virgo gravitational-wave detector in Italy and KAGRA in Japan. In January 2025, during LVK collaboration’s current observation run, LIGO picked up on the collision of 2 black holes 1.3 billion light-years away.

“This specific collision involved 2 black holes that looked pretty much identical to the first 2 we saw,” says Isi. “Intrinsically, the signal is equally loud, but our detectors are just so much more high fidelity now.

“We’re able to analyse the signal in ways that just weren’t possible 10 years ago.”

The researchers studied the event from the moment the black holes first collided, until the merged black hole settled into its new state just milliseconds later.

The final reverberations, or ‘ringdown’, can be likened to the way a bell rings when it is struck.

“Ten milliseconds sounds really short, but our instruments are so much better now that this is enough time for us to really analyse the ringing of the final black hole,” Isi says. “With this new detection, we have an exquisitely detailed view of the signal both before and after the black hole merger.”

This allowed the team to calculate the mass and spin of the black hole to determine its surface area. They found that while the initial black holes had a total surface area of 240,000km², this increased to about 400,000km² after merging.

The observations confirm a foundational idea proposed by British physicist Stephen Hawking in 1972, which predicts that the surface area of a black hole’s event horizons can never decrease.

Hawking’s area theorem – also known as the second law of black hole mechanics – mirrors the second law of thermodynamics, which says that entropy (disorder) can only increase. The theorem led to the realisation that black holes are thermodynamic objects.

“It’s really profound that the size of a black hole’s event horizon behaves like entropy,” Isi says.

“It has very deep theoretical implications and means that some aspects of black holes can be used to mathematically probe the true nature of space and time.

“It tells us that general relativity knows something about the quantum nature of these objects and that the information, or entropy, contained in a black hole is proportional to its area.”

The researchers also confirmed that the merged black hole was consistent with what is known as the ‘Kerr metric’.

In 1963, New Zealand mathematician Roy Kerr solved Albert Einstein’s field equations of general relativity and showed that black holes can be described by just 2 characteristics: spin and mass.

“We’ve found some of the strongest evidence yet that astrophysical black holes are the black holes predicted from Albert Einstein’s theory of general relativity,” says Isi.

“Two black holes with the same mass and spin are mathematically identical. It’s very unique to black holes.”

Gravitational wave detectors are only expected to become more sensitive in the next decade, which will allow for even more rigorous tests of black hole characteristics.

“Listening to the tones emitted by these black holes is our best hope for learning about the properties of the extreme space-times they produce,” says astrophysicist Will Farr, who co-led the research.

“As we build more and better gravitational wave detectors, the precision will continue to improve.”

As a developer with a passion for state machines, I’ve often found myself inspired by articles like “A Complete State Machine Made with HTML Checkboxes and CSS.” The power of pure CSS-driven state machines intrigued me, and I began to wonder: could I create something simpler, more interactive, and without the use of macros? This led to a project where I built an elevator simulation in CSS, complete with direction indicators, animated transitions, counters, and even accessibility features.

In this article, I’ll walk you through how I used modern CSS features — like custom properties, counters, the :has() pseudo-class, and @property — to build a fully functional, interactive elevator that knows where it is, where it’s headed, and how long it’ll take to get there. No JavaScript required.

Defining the State with CSS Variables

The backbone of this elevator system is the use of CSS custom properties to track its state. Below, I define several @property rules to allow transitions and typed values:

@property --current-floor {
  syntax: "<integer>";
  initial-value: 1;
  inherits: true;
}

@property --previous {
  syntax: "<number>";
  initial-value: 1;
  inherits: true;
}

@property --relative-speed {
  syntax: "<number>";
  initial-value: 4;
  inherits: true;
}

@property --direction {
  syntax: "<integer>";
  initial-value: 0;
  inherits: true;
}

These variables allow me to compare the elevator’s current floor to its previous one, calculate movement speed, and drive animations and transitions accordingly.

A regular CSS custom property (--current-floor) is great for passing values around, but the browser treats everything like a string: it doesn’t know if 5 is a number, a color, or the name of your cat. And if it doesn’t know, it can’t animate it.

That’s where @property comes in. By “registering” the variable, I can tell the browser exactly what it is (<number>, <length>, etc.), give it a starting value, and let it handle the smooth in-between frames. Without it, my elevator would just snap from floor to floor,  and that’s not the ride experience I was going for.

A Simple UI: Radio Buttons for Floors

Radio buttons provide the state triggers. Each floor corresponds to a radio input, and I use :has() to detect which one is selected:

<input type="radio" id="floor1" name="floor" value="1" checked>
<input type="radio" id="floor2" name="floor" value="2">
<input type="radio" id="floor3" name="floor" value="3">
<input type="radio" id="floor4" name="floor" value="4">

.elevator-system:has(#floor1:checked) {
  --current-floor: 1;
  --previous: var(--current-floor);
}

.elevator-system:has(#floor2:checked) {
  --current-floor: 2;
  --previous: var(--current-floor);
}

This combination lets the elevator system become a state machine, where selecting a radio button triggers transitions and calculations.

Motion via Dynamic Variables

To simulate elevator movement, I use transform: translateY(...) and calculate it with the --current-floor value:

.elevator {
  transform: translateY(calc((1 - var(--current-floor)) * var(--floor-height)));
  transition: transform calc(var(--relative-speed) * 1s);
}

The travel duration is proportional to how many floors the elevator must traverse:

--abs: calc(abs(var(--current-floor) - var(--previous)));
--relative-speed: calc(1 + var(--abs));

Let’s break that down:

• --abs gives the absolute number of floors to move.
• --relative-speed makes the animation slower when moving across more floors.

So, if the elevator jumps from floor 1 to 4, the animation lasts longer than it does going from floor 2 to 3. All of this is derived using just math expressions in the CSS calc() function.

Determining Direction and Arrow Behavior

The elevator’s arrow points up or down based on the change in floor:

--direction: clamp(-1, calc(var(--current-floor) - var(--previous)), 1);

.arrow {
  scale: calc(var(--direction) * 2);
  opacity: abs(var(--direction));
  transition: all 0.15s ease-in-out;
}

Here’s what’s happening:

• The clamp() function limits the result between -1 and 1.
• 1 means upward movement, -1 is downward, and 0 means stationary.
• This result is used to scale the arrow, flipping it and adjusting its opacity accordingly.

It’s a lightweight way to convey directional logic using math and visual cues with no scripting.

Simulating Memory with --delay

CSS doesn’t store previous state natively. I simulate this by delaying updates to the --previous property:

.elevator-system {
  transition: --previous calc(var(--delay) * 1s);
  --delay: 1;
}

While the delay runs, the --previous value lags behind the --current-floor. That lets me calculate direction and speed during the animation. Once the delay ends, --previous catches up. This delay-based memory trick allows CSS to approximate state transitions normally done with JavaScript.

Floor Counters and Unicode Styling

Displaying floor numbers elegantly became a joy thanks to CSS counters:

#floor-display:before {
  counter-reset: display var(--current-floor);
  content: counter(display, top-display);
}

I defined a custom counter style using Unicode circled numbers:

@counter-style top-display {
  system: cyclic;
  symbols: "\278A" "\2781" "\2782" "\2783";
  suffix: "";
}

The \278A to \2783 characters correspond to the ➊, ➋, ➌, ➃ symbols and give a unique, visual charm to the display. The elevator doesn’t just say “3,” but displays it with typographic flair. This approach is handy when you want to go beyond raw digits and apply symbolic or visual meaning using nothing but CSS.

Accessibility with aria-live

Accessibility matters. While CSS can’t change DOM text, it can still update screenreader-visible content using ::before and counter().

<div class="sr-only" aria-live="polite" id="floor-announcer"></div>

#floor-announcer::before {
  counter-reset: floor var(--current-floor);
  content: "Now on floor " counter(floor);
}

Add a .sr-only class to visually hide it but expose it to assistive tech:

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
}

This keeps the experience inclusive and aligned with accessibility standards.

Practical Applications of These Techniques

This elevator is more than a toy. It’s a blueprint. Consider these real-world uses:

• Interactive prototypes without JavaScript
• Progress indicators in forms using live state
• Game UIs with inventory or status mechanics
• Logic puzzles or educational tools (CSS-only state tracking!)
• Reduced JavaScript dependencies for performance or sandboxed environments

These techniques are especially useful in static apps or restricted scripting environments (e.g., emails, certain content management system widgets).

Final Thoughts

What started as a small experiment turned into a functional CSS state machine that animates, signals direction, and announces changes, completely without JavaScript. Modern CSS can do more than we often give it credit for. With :has(), @property, counters, and a bit of clever math, you can build systems that are reactive, beautiful, and even accessible.

If you try out this technique, I’d love to see your take. And if you remix the elevator (maybe add more floors or challenges?), send it my way!

CSS Elevator: A Pure CSS State Machine With Floor Navigation originally published on CSS-Tricks, which is part of the DigitalOcean family. You should get the newsletter.