Niels Leenheer

html5test@front-end.social

CTO of Salonhub. Creator of <a href="https://html5test.com" target="_blank" rel="nofollow noopener" translate="no">https://html5test.com</a>, writes at <a href="https://nielsleenheer.com" target="_blank" rel="nofollow noopener" translate="no">https://nielsleenheer.com</a>, team @FronteersConf, Google Developers Expert, Invite me to speak at your event.

Posts

Post #4220183
RE: https://front-end.social/@html5test/116686493760532281 Every time I decide to write a talk I underestimate the time I need. I do have a rough idea, but there is this whole period of me just making random slides. Sometimes weeks. Then suddenly I am happy. Build the rest of the talk in a day or two. Way too long. Cut in half. And it just fits together.
Post #4220182
On my way to #cssday, having a stop with some coffee and working on finishing my demos. What can go wrong. Totally prepared. Like a professional.
Post #4220181
A PSA for the #cssday attendees: It is perfectly safe to attend this year. Left my CSS Flamethrower at home. Apparently they don’t want me to burn the venue down. But no worries. I am only bringing an oscilloscope - it been repaired since it exploded last year - and lasers. Perfectly safe.
Post #4220180
Dropped my stuff off at the #cssday venue. Like you do. Totally normal.
Post #4220179
Today exactly 10 years ago, I spoke at CSS Day. Around that time I created a list of a handful of conference that I would love to speak at. And I am so lucky that was able to tick off most of them over the last 10 years. I even got to speak again at CSS Day last week. Just one left... for now.
Post #4220178
It&#39;s been a great year for conferences. I&#39;ve spoken at @btconf and @cssday and I&#39;ve been so lucky to attend so many others, like State of the Browser, Web Day Out and Smashing Conference. It&#39;s sharing knowledge, learning and getting inspired. But mostly the community. I will be posting about some conference that you should visit this fall. I will be at all of them – either organising myself or speaking. If you have any more tips for some great conferences tha...
Post #4220177
First up: Fronteers Dark Mode in Dordrecht 🇳🇱 on October 2nd. With Cyd Stumpel, @heydon, @csswizardry, @tunetheweb and Anjana Vakil. And @jaffathecake as our MC. An amazing location and tickets only cost €99, and include dinner. Don&#39;t miss this! 🎟️ fronteersconf.org
Post #4220176
Next: @ffconf in Brighton🇬🇧 This conference has been on my list for more than 10 years. I&#39;ve heard so many great things, but somehow never managed to attend. But this year I am not only heading over to Brighton, but I&#39;ll actually be on stage. Tickets will be on sale next week: 🎟️ 2026.ffconf.org
Post #4220175
Next: HalfStack is back! November 26th in Vienna🇦🇹 Another favourite. I am kind of part of the furniture, because this is going to be the 15th time I&#39;m speaking at HalfStack 😅 Tickets are just €200 euro and with this code you&#39;ll get 20% off: Niels_HSVienna26_Awesome20 🎟️ halfstackconf.com/vienna
Post #4220174
Not this fall, but the this conference needs to be included as well: State of the Browser organised by @webstandards will be back in 2027 on the 6th of March in the Barbican in London🇬🇧 I&#39;ve already got my ticket – just £80, which is a steal. 🎟️ 2027.stateofthebrowser.com
Post #4220173
The #cssday photos have been published and they are great. Love them. https://cssday.nl/2026/pix/photos/ But these... These made my day. These were taken during my talk and it makes all of the work I put into it worth it. ❤️
Post #2551853
This is happening! Multi-player cssDOOM death match. Rendering was already pretty much decoupled from gameplay, so the two side-by-side viewports were *almost* free. Still so much work to do, but made significant progress. In other news, I did not get much sleep last night.
Post #2528335
Made progress with cssDOOM last evening. Created a special multi-player deathmatch version for CSS Day that runs in kiosk mode. It uses a video wall controller to split up the screen into sections. On the computer it is just one full screen window, but it drives two separate screens.
Post #2314769
Am I really doing this? Maybe... Not even sure if I can pull this off in about a month or so before CSS Day. Wouldn&#39;t it be cool if you could play cssDOOM during the breaks and try to beat other attendees in a two-player Death Match game. And I still have to write my talk too... https://cssday.nl
Post #1812139
My office is in utter chaos. Tomorrow I am leaving for Düsseldorf for @btconf and I’ve never had so much tech to take with me. The talk is done. Has been for a week. But this is me practicing the demos and figuring out the tech that I need to bring.
Post #1468003
Arrived in Amsterdam for @smashingconf and booked an apartment for the coming days. But… I did not expect to step into a Rembrandt or Vermeer painting… 🤩
Post #1468002
First talk of the year is done: CSS is DOOMed, which was just a very last minute idea for the @smashingconf Jam Sessions. 10 minutes. No preparations. No slides. Off the cuff. But I had lots of fun playing cssDOOM and showing how it works under the hood.
Post #1468001
HTML DOM in Canvas? No. DOOM-ception in Canvas. Maybe I should be working on my slides for Friday, instead I&#39;m at @smashingconf.com creating a playable DOOM terminal in my cssDOOM project. It is a Canvas with an iframe of cssDOOM. And... it works. You can play DOOM in DOOM.
Post #1467998
Most of my talk preparations follow this pattern: 1. Idea 2. Worry about having enough content 3. Worry more about finishing 20 minutes early 4. Make slides 5. Practice 6. Panic, because it is 20 minute over time 7. Remove about a third of my talk 8. Panic, because I removed all the good jokes...
Post #1268418
RE: https://mastodon.social/@cssday/116244197568782653 So happy to be back on the CSS Day stage this June with so many other fantastic speakers. And I can&#39;t wait to show what I&#39;ve been working on the last year or two. Yes it will be about Doom, Lasers and CSS, and so much more. ✨ I do feel I&#39;ve hit peak talk title with &quot;CSS Doom Laser&quot;.
Post #1116850
Next week is @smashingconf week. I&#39;ve never been before and can&#39;t wait to be there as an attendee. On Monday there is the Jam Session, where I will be giving a 10 minute run-through of cssDoom. No slides, just me playing DOOM and showing how I build it. https://smashingconf.com/amsterdam-2026/jam-session
Post #1116849
Over the last week I&#39;ve fixed some cssDOOM issues and improved the gameplay to better match the original game. And the best part – because it is just a website, you don&#39;t have to download any updates. Best browser to run this is still latest Firefox, with Safari a good second. https://cssdoom.wtf/
Post #1116848
CSS Flamethrower 🔥 We definitely need dedicated CSS specification for this. The flamethrower is connected with DMX and WebUSB. All DMX devices including lamps and stage FX devices get a DOM element with an id. You can use CSS to set colours or... throw flames.
Post #1116847
Is it just me, or has Keynote has become terrible to use lately. Copying text blocks changes the font.... Copy source code... pasting a table?!?!
Post #1011622
Spending my Saturday morning soldering components for my BadClock because even if I look at it sideways, it falls apart. And not intentionally. I am bit scared to plug it in because Raspberry Pi’s are not cheap. And I already have a proper smoke machine.
Post #1011621
Take a Joy-Con and connect it with WebHID, draw a picture in the air and capture it with the sensors. Create an SVG path and insert in the DOM. Apply CSS styling. Sample the DOM and use WebUSB to convert to ILDA and send it to a laser projector. I created the worlds most complicated laserpointer…
Post #1011620
Great! My clock now randomly thinks it is a VCR. And nobody knows how to set the time on a VCR so it just blinks 12:00. Also it sometimes it forgets to reset after midnight so it goes from 23:59 to 24:00 to 25:00 and on. And yes. I am using a round display for a square digital clock…
Post #1011619
Putting the final touches on audio input for the DMX/Laser controller project. It analyses the audio and sets a class every time it detects a beat. That allows animations to start, or lights to change colour or the laser to draw patterns. Crazy that all of this is build using web technology.
Post #1011618
Sometimes I feel like I have too many projects. I move from one to the other and old projects get ignored because I am working on something new and shiny. But that chaos also helps me be creative and challenge me to improve my skills. But today I&#39;m feeling like a mad professor. In a good way.
Post #1011616
RE: https://mastodon.social/@btconf/116362469509964678 I am so honoured to be part of #btconf this year. This conference has been such a huge inspiration to me over the years. Been working on this talk for at least a year and expect chaotic energy with lots of weird and wonderful web experiments.