Niels Leenheer
@html5test.com
580 followers 270 following 160 posts
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.
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html5test.com
Yes!

I use this in one of my talks about the resilience of HTML. It's a joke, but also to point out that very little just is removed from the web platform. Yes, marque may be "deprecated" or "obsolete", it is still part of the standard and works in browsers.

Now <blink> on the other hand...
html5test.com
Thanks! This is great! Exactly what I was looking for.
html5test.com
So this is either very clever, or I am overlooking something very obvious. Which is it? Is there an easier way to do this?

@bram.us @una.im @miriam.codes

(Oh... and it crashes Safari... so... yeah)
html5test.com
I was reading through the CSS Anchored Position spec and I just could not figure out how to make a tooltip that points towards the anchor. To me that was kind of an obvious requirement as this is a really common pattern for tooltips.

This is what I ended up with:
codepen.io/NielsLeenhee...
Anchored Positioning Tip pointing to anchor
...
codepen.io
html5test.com
The thing that causes Safari to freeze is the position-anchor on a pseudo element. There is nothing really out of the ordinary. The pseudo has position fixed and I only set the top of the pseudo to the bottom of the anchor and use justify-self.

@jensimmons.bsky.social
html5test.com
Is it just me? Or does this codepen just causes Safari 26 to freeze? codepen.io/NielsLeenhee...
Untitled
...
codepen.io
html5test.com
Playing around with CSS Anchor Positioning in Safari 26... And it is not going well..
Reposted by Niels Leenheer
strandjunker.com
“Terrible things are happening outside. Poor helpless people are being dragged out of their homes. Families are torn apart. Men, women, and children are separated. Children come home from school to find that their parents have disappeared.”

Diary of Anne Frank
January 13, 1943
Reposted by Niels Leenheer
philhawksworth.dev
Hahaha. All conference speakers need this.
dylanbeatt.ie
I'm in Dordrecht for @fronteers.bsky.social Dark Mode conf tomorrow, and they left a little gift pack of speaker goodies in my hotel room including this, and I think it's absolutely delightful. ❤️
It's one of those things you hang on your hotel room door but instead of saying DO NOT DISTURB it says DON'T WORRY. I AM NOT TALKING TO MYSELF. I AM REHEARSING MY TALK.
html5test.com
Ha! I remember seeing this talk live at the Polymer Summit in Amsterdam.
html5test.com
Not much hope for Liquid Glass improvements in iOS 26.1…
html5test.com
From what I heard there are only a very limited number of tickets left. Ticket sales will close at midnight. So last chance for a great evening at Fronteers Dark Mode!

And it is only €49 for Fronteers members and €99 for regular tickets, which is a steal.
fronteers.bsky.social
What if a frontend conference started at 4PM and kept going until midnight?

🍷 Drinks, vibes, and five great talks
💻 HTML, CSS, sustainability, accessibility & more
📍 Cinema De Witt, Dordrecht
🎟 fronteersconf.org
A promotional banner for “Fronteers Dark Mode”. In the background is a photo of the outdoor terrace of Cinema De Witt in Dordrecht, with people sitting, chatting, and enjoying food and drinks in a cozy, well-lit evening setting. In the foreground, a large yellow speech bubble contains the event text:
“Friday night. Frontend. Fronteers Dark Mode!
Join us on Friday, October 3rd, 2025, at Cinema De Witt in Dordrecht for an intimate evening of frontend talks and community vibes – from 4PM to after midnight.”
Reposted by Niels Leenheer
fronteers.bsky.social
🎨 Speaker spotlight: Rune Devuyst – The Dark Side of Bright Colours

Colour isn’t just a visual choice — it shapes accessibility and device energy use. Rune explores how your palette impacts OLED screens, contrast, and even sustainability. ⚡

🎟️ Tickets & info: fronteersconf.org
Black and white portrait of Rune Devuyst smiling, with text on a light purple background:
“Rune Devuyst — The Dark Side of Bright Colours: The Impact of Your Colour Choices.
Fronteers Dark Mode — Fri 3 Oct. 2025 – Dordrecht.”
Reposted by Niels Leenheer
fronteers.bsky.social
🌱 Thorsten Jonas – Beyond User-Centricity

Great UX shouldn't come at the planet’s expense. Thorsten shows how to design sustainable, responsible digital products—by default.

🗓 Fronteers Dark Mode · Oct 3 · Dordrecht
🎟️ fronteersconf.org
Black-and-white photo of Thorsten Jonas smiling, wearing glasses and a blazer. To the left of the image, on a yellow background, the text reads:
“Thorsten Jonas
Beyond User-Centricity – Designing sustainable digital Products
Fronteers Dark Mode
Fri 3 Oct. 2025 – Dordrecht.”
Reposted by Niels Leenheer
fronteers.bsky.social
🎸 Dylan Beattie brings Rockstar 2.0 to Fronteers Dark Mode!

A joke language based on Bon Jovi — powered by real tech like .NET, JS & WASM.
Expect laughs, insights & maybe a Rockstar cert. 🤘

🗓 Oct 3 · Dordrecht
🎟️ fronteersconf.org
Black-and-white speaker card featuring Dylan Beattie. On the left, bold text reads: “Dylan Beattie – How To Be a Rockstar Developer.” Below that, “Fronteers Dark Mode – Fri 3 Oct. 2025 – Dordrecht.” On the right, a portrait of Dylan Beattie smiling, with long hair and a goatee, wearing a leather vest over a dark shirt. The background is blurred. The design uses a curved red background on the left side for contrast.
html5test.com
At least our phones will be usable again in *checks calendar* 2029.
Reposted by Niels Leenheer
ericwbailey.website
My main takeaway so far from this @inclusivedesign24.bsky.social talk about BBC app design is that Apple's liquid glass is absolute dogshit when it comes to accessibility 😬
Screenshot of a slide titled "BBC Sounds navigation". There are three rows, each containing a bottom app navigation bar. The first shows a row of labeled icons with clear contrast for both the active navigation section and inactive navigation sections. The second row shows a variant of the navigation bar where the inactive navigation sections have a low-contrast color treatment. The third row shows a liquid glass treatment for the navigation, where the contrast between the background and the foreground is difficult to discern.
Reposted by Niels Leenheer
fronteers.bsky.social
What if a frontend conference started at 4PM and kept going until midnight?

🍷 Drinks, vibes, and five great talks
💻 HTML, CSS, sustainability, accessibility & more
📍 Cinema De Witt, Dordrecht
🎟 fronteersconf.org
A promotional banner for “Fronteers Dark Mode”. In the background is a photo of the outdoor terrace of Cinema De Witt in Dordrecht, with people sitting, chatting, and enjoying food and drinks in a cozy, well-lit evening setting. In the foreground, a large yellow speech bubble contains the event text:
“Friday night. Frontend. Fronteers Dark Mode!
Join us on Friday, October 3rd, 2025, at Cinema De Witt in Dordrecht for an intimate evening of frontend talks and community vibes – from 4PM to after midnight.”
Reposted by Niels Leenheer
halfstackconf.bsky.social
HalfStack London Highlights 🎥

Join us on the 12th of November 2025, at 93 Feet East, Shoreditch, for web development sessions, demos, music, quizzes, and karaoke with the developer community.

📅 Event details: halfstackconf.com/london

#HalfStack #HalfStackLondon #WebDevelopment #Coding
Reposted by Niels Leenheer
fronteers.bsky.social
🌒 Fronteers Dark Mode is coming!
A cozy, after-work frontend conference in Dordrecht on Friday, Oct 3.
🎤 5 talks · up to 100 people · 1 fun night until midnight

🎟 €49 for members / €99 for everyone else
👉 fronteersconf.org
Banner for “Fronteers Dark Mode”. In the background is a photo of the outdoor terrace of Cinema De Witt in Dordrecht, with people sitting, chatting, and enjoying food and drinks in a cozy, well-lit evening setting. In the foreground, a large yellow speech bubble contains the event text:
“Friday night. Frontend. Fronteers Dark Mode!
Join us on Friday, October 3rd, 2025, at Cinema De Witt in Dordrecht for an intimate evening of frontend talks and community vibes – from 4PM to after midnight.
Reposted by Niels Leenheer
halfstackconf.bsky.social
𝐇𝐚𝐥𝐟𝐒𝐭𝐚𝐜𝐤 𝐋𝐨𝐧𝐝𝐨𝐧 𝟐𝟎𝟐𝟓 𝐢𝐬 𝐜𝐨𝐦𝐢𝐧𝐠ⵑ 🎉

Join us on the 12th of November at 93 Feet East, Shoreditch, for a day of creative web presos, live demos, and plenty of fun with the dev community.

✨ Expect great presenters, music, quizzes, and even karaoke.

📅 Save the date → halfstackconf.com/london
Reposted by Niels Leenheer
html5test.com
With the upcoming release of iOS 26 and macOS 26, the user-agent string of Safari will change. I've tried out the beta's and gone over 1000's of lines in our logs to see what has changed and some changes are not what you expect!

nielsleenheer.com/articles/202...
User-Agent String for Safari 26 Explained
Discover the user-agent string for Safari 26, its significance, and the changes coming in iOS and macOS.
nielsleenheer.com