Niels Leenheer
@html5test.com
CTO of Salonhub. Creator of http://html5test.com, writes at http://nielsleenheer.com, team @FronteersConf, Google Developers Expert, Invite me to speak at your event.
Oooh. This is incredibly useful. Just the other day I tried if inherit works in a calc() function - it obviously doesn’t. But now inherit() does!
inherit() is now available to play with in Chrome Canary.
Here's some writing I did about it earlier:
How CSS inherit() Could Simplify Design Systems
www.alwaystwisted.com/articles/mak...
How inherit() Can Simplify Border‑Radius for Components
www.alwaystwisted.com/articles/mak...
🙏🖤
Here's some writing I did about it earlier:
How CSS inherit() Could Simplify Design Systems
www.alwaystwisted.com/articles/mak...
How inherit() Can Simplify Border‑Radius for Components
www.alwaystwisted.com/articles/mak...
🙏🖤
November 25, 2025 at 3:08 PM
Oooh. This is incredibly useful. Just the other day I tried if inherit works in a calc() function - it obviously doesn’t. But now inherit() does!
🔥🔥🔥
Lowest setting. CSS powered flamethrower!
Yes, it is really controlled by CSS. I can add MIDI inputs. Then use CSS to trigger animations and output the result to DMX for controlling the flamethrower.
Lowest setting. CSS powered flamethrower!
Yes, it is really controlled by CSS. I can add MIDI inputs. Then use CSS to trigger animations and output the result to DMX for controlling the flamethrower.
November 18, 2025 at 2:44 PM
🔥🔥🔥
Lowest setting. CSS powered flamethrower!
Yes, it is really controlled by CSS. I can add MIDI inputs. Then use CSS to trigger animations and output the result to DMX for controlling the flamethrower.
Lowest setting. CSS powered flamethrower!
Yes, it is really controlled by CSS. I can add MIDI inputs. Then use CSS to trigger animations and output the result to DMX for controlling the flamethrower.
Current status: working on side projects until the Cloudflare issue has been solved.
November 18, 2025 at 2:21 PM
Current status: working on side projects until the Cloudflare issue has been solved.
DevFest Warsaw is about to start. This is such a lovely space #devfest2025 #devfestwarsaw #googledevelopers
November 15, 2025 at 9:34 AM
DevFest Warsaw is about to start. This is such a lovely space #devfest2025 #devfestwarsaw #googledevelopers
Current mood:
youtu.be/Ra8gSw7Djvo?...
youtu.be/Ra8gSw7Djvo?...
Ren x The Skinner Brothers - Pink Heineken
YouTube video by Ren
youtu.be
November 14, 2025 at 7:31 PM
Current mood:
youtu.be/Ra8gSw7Djvo?...
youtu.be/Ra8gSw7Djvo?...
Arrived in Warsaw this evening for my penultimate conference of the year. Tomorrow DevFest Warsaw, then in a week and a half DevFest Malta.
Tonight a quiet night. We’re halfway November and I have only slept 4 nights in my own bed. I’ll need a couple of months rest after this.
#devfestwarsaw
Tonight a quiet night. We’re halfway November and I have only slept 4 nights in my own bed. I’ll need a couple of months rest after this.
#devfestwarsaw
November 14, 2025 at 5:31 PM
Arrived in Warsaw this evening for my penultimate conference of the year. Tomorrow DevFest Warsaw, then in a week and a half DevFest Malta.
Tonight a quiet night. We’re halfway November and I have only slept 4 nights in my own bed. I’ll need a couple of months rest after this.
#devfestwarsaw
Tonight a quiet night. We’re halfway November and I have only slept 4 nights in my own bed. I’ll need a couple of months rest after this.
#devfestwarsaw
Okay, one more. I just loooooove the reflection here. So good. Doesn’t look like shit at all. No siree, ship it!
November 14, 2025 at 1:16 PM
Okay, one more. I just loooooove the reflection here. So good. Doesn’t look like shit at all. No siree, ship it!
Reposted by Niels Leenheer
Most relatable conference talk silde ever, courtesy of @html5test.com at #HalfStack
November 12, 2025 at 10:19 PM
Most relatable conference talk silde ever, courtesy of @html5test.com at #HalfStack
On my way to Heathrow after another fantastic edition of @halfstackconf.bsky.social.
Happy with how my talk about Baseline went and then I did another unplanned 10 minute talk about one of my side projects that I literally wrote the night before, after the speaker dinner 😅
Happy with how my talk about Baseline went and then I did another unplanned 10 minute talk about one of my side projects that I literally wrote the night before, after the speaker dinner 😅
November 13, 2025 at 9:55 AM
On my way to Heathrow after another fantastic edition of @halfstackconf.bsky.social.
Happy with how my talk about Baseline went and then I did another unplanned 10 minute talk about one of my side projects that I literally wrote the night before, after the speaker dinner 😅
Happy with how my talk about Baseline went and then I did another unplanned 10 minute talk about one of my side projects that I literally wrote the night before, after the speaker dinner 😅
Reposted by Niels Leenheer
It’s alive and on stage! cc: @nerdy.dev
November 12, 2025 at 12:43 PM
It’s alive and on stage! cc: @nerdy.dev
Just got home. First thing my 11-year old said to me: Dad, did you buy a flamethrower…?
Eh. Yes. Yes, I did. 🔥
Eh. Yes. Yes, I did. 🔥
November 8, 2025 at 3:31 PM
Just got home. First thing my 11-year old said to me: Dad, did you buy a flamethrower…?
Eh. Yes. Yes, I did. 🔥
Eh. Yes. Yes, I did. 🔥
Almost home again after a couple of amazing days at @beyondtellerrand.com. Thank you so much @marcthiele.com!
It was so lovely seeing everybody again. After spending a couple hours at home I am off again to London for @halfstackconf.bsky.social and then straight to Warsaw for DevFest.
It was so lovely seeing everybody again. After spending a couple hours at home I am off again to London for @halfstackconf.bsky.social and then straight to Warsaw for DevFest.
November 8, 2025 at 1:58 PM
Almost home again after a couple of amazing days at @beyondtellerrand.com. Thank you so much @marcthiele.com!
It was so lovely seeing everybody again. After spending a couple hours at home I am off again to London for @halfstackconf.bsky.social and then straight to Warsaw for DevFest.
It was so lovely seeing everybody again. After spending a couple hours at home I am off again to London for @halfstackconf.bsky.social and then straight to Warsaw for DevFest.
@nerdy.dev This is happening. MIDI → CSS → DMX → 🔥
November 8, 2025 at 10:03 AM
@nerdy.dev This is happening. MIDI → CSS → DMX → 🔥
Reposted by Niels Leenheer
#js developers 📣! There's still time to sign up for @halfstackconf.bsky.social London on Wed 12th November. There's some great talks on the list, including myself talking about #vectorsearch.
Here's my 10% off code if you still haven't got your 🎫 (😱):
ti.to/halfstack/ha...
See you there! 👋
Here's my 10% off code if you still haven't got your 🎫 (😱):
ti.to/halfstack/ha...
See you there! 👋
November 5, 2025 at 12:31 PM
#js developers 📣! There's still time to sign up for @halfstackconf.bsky.social London on Wed 12th November. There's some great talks on the list, including myself talking about #vectorsearch.
Here's my 10% off code if you still haven't got your 🎫 (😱):
ti.to/halfstack/ha...
See you there! 👋
Here's my 10% off code if you still haven't got your 🎫 (😱):
ti.to/halfstack/ha...
See you there! 👋
Looking for some random thing on AliExpress when suddenly… Hey! I could use a flame thrower! It would be fun to connect it to the web and…
November 5, 2025 at 10:02 AM
Looking for some random thing on AliExpress when suddenly… Hey! I could use a flame thrower! It would be fun to connect it to the web and…
I guess Deutsche Bahn is going to Deutsche Bahn. Good decision to travel the day before. I will be late, but I’ll get to Berlin.
Lessons learned from last year visiting @beyondtellerrand.com where I missed the first two talks and got stranded in the middle of the night on my way back home.
Lessons learned from last year visiting @beyondtellerrand.com where I missed the first two talks and got stranded in the middle of the night on my way back home.
November 5, 2025 at 9:50 AM
I guess Deutsche Bahn is going to Deutsche Bahn. Good decision to travel the day before. I will be late, but I’ll get to Berlin.
Lessons learned from last year visiting @beyondtellerrand.com where I missed the first two talks and got stranded in the middle of the night on my way back home.
Lessons learned from last year visiting @beyondtellerrand.com where I missed the first two talks and got stranded in the middle of the night on my way back home.
And from London to Warsaw where I will join DevFest Warsaw and give a talk about Project Fugu.
I will show how my company build a completely browser based cash register application that is using WebUSB, WebHID, WebSerial for talking to point of sale devices.
🎟️ sites.google.com/view/devfest...
I will show how my company build a completely browser based cash register application that is using WebUSB, WebHID, WebSerial for talking to point of sale devices.
🎟️ sites.google.com/view/devfest...
November 4, 2025 at 1:43 PM
And from London to Warsaw where I will join DevFest Warsaw and give a talk about Project Fugu.
I will show how my company build a completely browser based cash register application that is using WebUSB, WebHID, WebSerial for talking to point of sale devices.
🎟️ sites.google.com/view/devfest...
I will show how my company build a completely browser based cash register application that is using WebUSB, WebHID, WebSerial for talking to point of sale devices.
🎟️ sites.google.com/view/devfest...
And from Berlin straight to London for HalfStack where I will be giving a new talk about Baseline.
I'll be talking about the issues that web developers have keeping up with the ever expanding web platform and how to deal with browser compatibility and interoperability.
🎟️ halfstackconf.com/london
I'll be talking about the issues that web developers have keeping up with the ever expanding web platform and how to deal with browser compatibility and interoperability.
🎟️ halfstackconf.com/london
HalfStack | London
halfstackconf.com
November 4, 2025 at 1:38 PM
And from Berlin straight to London for HalfStack where I will be giving a new talk about Baseline.
I'll be talking about the issues that web developers have keeping up with the ever expanding web platform and how to deal with browser compatibility and interoperability.
🎟️ halfstackconf.com/london
I'll be talking about the issues that web developers have keeping up with the ever expanding web platform and how to deal with browser compatibility and interoperability.
🎟️ halfstackconf.com/london
Going to be a busy two weeks!
Traveling to Berlin tomorrow for Beyond Tellerrand @beyondtellerrand.com. I've been looking forward to this for at least since the Dusseldorf edition this spring. Can't wait!
I see there are still tickets available, so join us!
🎟️ beyondtellerrand.com/events/berli...
Traveling to Berlin tomorrow for Beyond Tellerrand @beyondtellerrand.com. I've been looking forward to this for at least since the Dusseldorf edition this spring. Can't wait!
I see there are still tickets available, so join us!
🎟️ beyondtellerrand.com/events/berli...
Tickets for beyond tellerrand in Berlin 2025
beyond tellerrand is the affordable single-track event where creativity and technology meet. Taking place in Düsseldorf and Berlin these days with 500+ attendees each in a renowned, familiar and frien...
beyondtellerrand.com
November 4, 2025 at 1:35 PM
Going to be a busy two weeks!
Traveling to Berlin tomorrow for Beyond Tellerrand @beyondtellerrand.com. I've been looking forward to this for at least since the Dusseldorf edition this spring. Can't wait!
I see there are still tickets available, so join us!
🎟️ beyondtellerrand.com/events/berli...
Traveling to Berlin tomorrow for Beyond Tellerrand @beyondtellerrand.com. I've been looking forward to this for at least since the Dusseldorf edition this spring. Can't wait!
I see there are still tickets available, so join us!
🎟️ beyondtellerrand.com/events/berli...
Reposted by Niels Leenheer
𝟏𝟐 𝐝𝐚𝐲𝐬 𝐥𝐞𝐟𝐭 𝐮𝐧𝐭𝐢𝐥 𝟏𝟐 𝐍𝐨𝐯𝐞𝐦𝐛𝐞𝐫ⵑ
Be part of the final HalfStack London, a full day of creative web explorations, live demos, music, quizzes, and karaoke! 🎉
📅 12 Nov 2025 | 93 Feet East, Shoreditch
👉 halfstackconf.com/london
#HalfStack #HalfStackLondon
Be part of the final HalfStack London, a full day of creative web explorations, live demos, music, quizzes, and karaoke! 🎉
📅 12 Nov 2025 | 93 Feet East, Shoreditch
👉 halfstackconf.com/london
#HalfStack #HalfStackLondon
October 31, 2025 at 6:22 PM
𝟏𝟐 𝐝𝐚𝐲𝐬 𝐥𝐞𝐟𝐭 𝐮𝐧𝐭𝐢𝐥 𝟏𝟐 𝐍𝐨𝐯𝐞𝐦𝐛𝐞𝐫ⵑ
Be part of the final HalfStack London, a full day of creative web explorations, live demos, music, quizzes, and karaoke! 🎉
📅 12 Nov 2025 | 93 Feet East, Shoreditch
👉 halfstackconf.com/london
#HalfStack #HalfStackLondon
Be part of the final HalfStack London, a full day of creative web explorations, live demos, music, quizzes, and karaoke! 🎉
📅 12 Nov 2025 | 93 Feet East, Shoreditch
👉 halfstackconf.com/london
#HalfStack #HalfStackLondon
If you find yourself wondering if you really need four oscilloscopes... then it is already too late and you might as well buy that fifth one.
Okay, two of them are in working condition. Barely. One is at the repair shop for a blown capacitor. One worked for 5 minutes.
So yes. I do need one more.
Okay, two of them are in working condition. Barely. One is at the repair shop for a blown capacitor. One worked for 5 minutes.
So yes. I do need one more.
October 30, 2025 at 6:38 PM
If you find yourself wondering if you really need four oscilloscopes... then it is already too late and you might as well buy that fifth one.
Okay, two of them are in working condition. Barely. One is at the repair shop for a blown capacitor. One worked for 5 minutes.
So yes. I do need one more.
Okay, two of them are in working condition. Barely. One is at the repair shop for a blown capacitor. One worked for 5 minutes.
So yes. I do need one more.
Reposted by Niels Leenheer
🔥 Hot off the press 🔥
You can you can finally style anchored elements based on their fallback position in CSS!
Meet the CSS anchored container query 🤝
container-type: anchored
@container anchored(fallback:)
(landing in Chrome 143)
developer.chrome.com/blog/anchore...
You can you can finally style anchored elements based on their fallback position in CSS!
Meet the CSS anchored container query 🤝
container-type: anchored
@container anchored(fallback:
(landing in Chrome 143)
developer.chrome.com/blog/anchore...
Detect fallback positions with anchored container queries from Chrome 143 | Blog | Chrome for Developers
Detect fallback positions with anchored container queries from Chrome 143
developer.chrome.com
October 30, 2025 at 1:39 PM
🔥 Hot off the press 🔥
You can you can finally style anchored elements based on their fallback position in CSS!
Meet the CSS anchored container query 🤝
container-type: anchored
@container anchored(fallback:)
(landing in Chrome 143)
developer.chrome.com/blog/anchore...
You can you can finally style anchored elements based on their fallback position in CSS!
Meet the CSS anchored container query 🤝
container-type: anchored
@container anchored(fallback:
(landing in Chrome 143)
developer.chrome.com/blog/anchore...
Only two more weeks until it is time for HalfStack London. Attending HalfStack is always a treat with great talks, fun people and good pizza.
I'll be speaking again this year about Baseline and how we can make informed choices about browser support in 2025.
🎟️ halfstackconf.com/london
I'll be speaking again this year about Baseline and how we can make informed choices about browser support in 2025.
🎟️ halfstackconf.com/london
October 29, 2025 at 11:08 AM
Only two more weeks until it is time for HalfStack London. Attending HalfStack is always a treat with great talks, fun people and good pizza.
I'll be speaking again this year about Baseline and how we can make informed choices about browser support in 2025.
🎟️ halfstackconf.com/london
I'll be speaking again this year about Baseline and how we can make informed choices about browser support in 2025.
🎟️ halfstackconf.com/london
Reposted by Niels Leenheer
𝐇𝐚𝐥𝐟𝐒𝐭𝐚𝐜𝐤 𝐋𝐨𝐧𝐝𝐨𝐧:
The fun, creative side of web development. 🎉
📅 12 Nov 2025 | 93 Feet East, Shoreditch
🎟️ halfstackconf.com/london
#HalfStack #HalfStackLondon
The fun, creative side of web development. 🎉
📅 12 Nov 2025 | 93 Feet East, Shoreditch
🎟️ halfstackconf.com/london
#HalfStack #HalfStackLondon
October 27, 2025 at 10:36 AM
𝐇𝐚𝐥𝐟𝐒𝐭𝐚𝐜𝐤 𝐋𝐨𝐧𝐝𝐨𝐧:
The fun, creative side of web development. 🎉
📅 12 Nov 2025 | 93 Feet East, Shoreditch
🎟️ halfstackconf.com/london
#HalfStack #HalfStackLondon
The fun, creative side of web development. 🎉
📅 12 Nov 2025 | 93 Feet East, Shoreditch
🎟️ halfstackconf.com/london
#HalfStack #HalfStackLondon
Reposted by Niels Leenheer
Welcome to a new week. I‘ll send the badges to the printer today. If you want your name to be printed, get your ticket for #btconf Berlin until noon. beyondtellerrand.com/events/berli...
beyond tellerrand - An event about the Web, design and technology
beyond tellerrand is the affordable single-track event where creativity and technology meet. Taking place in Düsseldorf and Berlin these days with 500+ attendees each in a renowned, familiar and frien...
beyondtellerrand.com
October 27, 2025 at 7:17 AM
Welcome to a new week. I‘ll send the badges to the printer today. If you want your name to be printed, get your ticket for #btconf Berlin until noon. beyondtellerrand.com/events/berli...