Has anyone written/built an `llms.txt` that they’re really happy with? And have you noticed it working/helping? I recently updated my research agent to check all websites for `/llms.txt` before diving straight into parsing pages of HTML and I’m looking forward to seeing if/how effective it is.

If you’re doing any reasonable amount of performance work, ensure you have a fresh browser profile with no ad blockers installed, and ensure this is unchecked (Chrome)! You’re only getting part of the picture otherwise.

For the last month or so, I’ve been playing Wordle against ChatGPT and keeping track of our scores. It’s incredibly close, but I’m just winning.

A great, succinct, informative write up from my pal @matuzo.at! Context-aware headings in HTML: www.matuzo.at/blog/2026/co...

It’s true…

Today, I spoke at the inaugural #DUNC26 in Hull—a real gem of a city. The conference packed so much diversity of content into a one-day, one-track event, BUT! My favourite takeaway is that every single speaker listed a personal site/blog in their slides. I visited every one of them. What a day.

🔍 I can’t help but feel like we’re missing something… Front-End’s Missing Metric: csswizardry.com/2026/06/fron...

🎤 I’m speaking at #LeedsJS TONIGHT! Free to attend. Be there or be aspect-ratio: 1; www.meetup.com/leeds-js/eve...

🩺 Meet Your Users Where They Are with Obs.js csswizardry.com/2026/05/meet...

An important update courtesy of @tunetheweb.com! csswizardry.com/2026/05/bett...

Show, don’t tell! A couple of years ago, I ran a custom INP workshop for a client, and built an interactive demo to show them what their site FEELS like. Today, I decided to polish it and publish it!

I’ve been working with a client who runs a lot of social media and ad campaigns, so we’ve been deploying the experimental `No-Vary-Search HTTP` header. It’s amazing to see it actually working! Read all about it here: csswizardry.com/2026/05/bett...

‼️ BEWARE! `font-family` Doesn’t Fall Back the Way You Think: csswizardry.com/2026/04/font...

Play with it here: jsbin.com/toriwawari/e...

PSA, this is why you keep seeing Times New Roman all over your site. #CSS #CLS #Typography

🎨 I gotta say, my latest is a little treasure trove: what even is `contain`?! csswizardry.com/2026/04/what...

I miss #WebDayOut :(

reading: What Is CSS Containment and How Can I Use It? csswizardry.com/2026/04/what... — my prayers were answered! Harry explains all 🙏 for my next wish...

100% agree with this! Browsers are AMAZING at loading a page in mostly the right way by default. There are lots of extra options (fetchpriority, loading=lazy) to tweak that further if you know with reasonably certainly that they could benefit from those. If it’s ambiguous, then leave it be.

🚫 When All You Can Do Is All or Nothing, Do Nothing For all you weekend warriors, advice for times of uncertainty. csswizardry.com/2026/03/when...

🇳🇱 Freshly back from a wonderful working week in The Hague. I shall never tire of this beautiful city.

Well, Brighton, you’ve been stunning as always. Thank you so much to @adactio.com and the @clearleft.com team for having me at #WebDayOut, an invigorating and inspiring shot in the arm to kick conference season off proper.

Me looking at standardised web APIs like… #WebDayOut

Hello and good morning from Brighton, where I attend #WebDayOut. If you want to follow along visually, here is my set of photos that document the day. More to follow. marcthiele.com/photos/web-d...

Slides from my #WebDayOut talk, ‘Build for the Web, Build on the Web, Build With the Web’. Incredibly proud of this one. speakerdeck.com/csswizardry/...

And we’re off! #WebDayOut

Hey, Bluesky! Have some blue sky. I’m in beautiful Brighton for @clearleft.com’s #WebDayOut tomorrow. Who else is here?

I’ve been consulting for 12 years and I still get a real rush every time an enquiry comes in. An amazing feeling!

Build for the Web, Build on the Web, Build with the Web csswizardry.com/2025/01/buil...

(Anyone traveling Schiphol to Centraal please be advised that Sprinter trains are anything but.)

🇬🇧 ✈️ 🇳🇱 To @perfnow.nl! My favourite week of the year.

You know you should be testing your site or app with low and mid-tier mobiles, but what exactly does that *mean* for 2025? What's low-end? What's mid-tier? What are people using right now? @csswizardry.com gets into which phones would work well, what emulations to use, and why it's important.

What a beautiful trip to Toronto for @fitc.ca. Thank you so much for having me.

Not only is @jpamental.bsky.social a really good friend, he’s an exceptionally good MC. You should hire him for your event.

If your company has just laid you off, sneak `v` and `version` into the allowlist before you leave 👀

Allowlisted params (e.g. ?utm_source) can be reused in HTTP cache!

[email protected] showed me this hyper elegant deep-link approach that @cloudflare.social provide: `dash dot cloudflare dot com/?to=/:account/:zone/speed/optimization/protocol` This lets you select your Cloudflare account and zone before taking you to its correct Protocol dashboard!

I recently started instrumenting both @cloudflare.social and browser cache hits/misses and the numbers, while obvious, are compelling. The best request is the one that never happens. Check that 0ms TTFB 😍 ℅ @speedcurve.com

Build for the web, Build on the web, Build with the web. An excellent take from @csswizardry.com on progressive enhancement, SPA frameworks and staying as close to the platform as possible. csswizardry.com/2025/01/buil...

🔮 I held three of my 1:1s in the last 24hr and it’s amazing to see (and shape) what folk are working on. Different project, different audiences, different scales, but all so fun to help out with.

I would wholeheartedly recommend this by the way. 2:1 salt:MSG used anywhere you’d use salt in a savoury context. Amazing on meat and green vegetables.

Huge news from @cloudflare.social! blog.cloudflare.com/the-rum-diar...

What a privilege to be speaking at one of @adactio.com’s events! It’s only taken about 15 years…

performance.now() is coming! As tooling improves, is performance testing becoming any easier? @csswizardry.com, who spends every day auditing client projects,, thinks confusion has increased. Let's ensure that every test we run has a purpose and gives us useful data. perfnow.nl/speakers.htm...

Friends and fans of Obs.js, please consider lending your vote for Interop 2026: github.com/web-platform...

I’ve spent a bit of the weekend doing some analysis of my newsletter and it’s blown me away. I’ve definitely been neglecting it. Over 4,000 of you with >55% open rate and >15% click rate. That’s way way WAY above the industry average. You folk are incredible! So supportive ❤️

🪄 If you’ve ever wondered where the name CSS Wizardry came from (and why on earth it stuck), I’m telling newsletter subscribers the full back story later today: csswizardry.com/newsletter/

This is one of the best talks I’ve ever seen. Give it 20 minutes of your weekend.

And if this interests you, I wrote about it OVER A DECADE ago: 24ways.org/2013/keeping...

I think a lot of folk tend to forget that @github.com Gists are Git repositories like any other, just lacking most of the GUI functionality. This means they’re a great place to store long-lived, version-controlled, distributed, shareable documents.