Customisable <select> and the friends we made along the way

Developers wanted a way to customise <select> for years, decades even, but what took so long, and what features landed along the way?

In this talk, we’ll look at a smorgasbord of web platform features that needed to land first, and how they worked their way through the standards process.

Jake Archibald

Jake Archibald is a developer of sorts working at Mozilla on web standards and developer relations.

Let's fix the web's text size

About 35% of phone users change their OS text size. Have you ever noticed, though, that when you increase the text size on your phone, nothing changes on websites?

I’ll show you the work we’ve done at the CSS Working Group to finally fix that, and how you can make sure your website respects the user’s text size preference.

Josh Tumath

Josh is a front-end developer who loves CSS. He has been a developer of the BBC’s Web Design System since it’s humble beginnings over six years ago. He also represents the BBC at the CSS Working Group, which he joined in the summer of 2024. He’s been making it up as he goes along since then.

He is a massive extrovert and loves meeting new people! Please say hello!

Putting the C in CSS Crimes

We all know that CSS is a programming language, so let's see what happens if we truly use it as one.

In this talk I'll show you how to to make interactive art and games: a CSS x86 CPU that runs C code, and some some classic Cohost CSS crimes.

Lyra Rebane

Lyra Rebane is a security researcher and former Cohoster from Estonia with a bunch of browser CVEs and a love for the web. She loves writing CSS, be it as a styling language for web design, or as a programming language for making games. Check out her cool website at lyra.horse.

Ana Rodrigues: MC

Ana works as a front-end developer at tech-for-good agency Hactar. She started coding as a teenager building fan sites, and has been working as a front-end developer for the last 12 years.

Nowadays, Ana spends most of her free time experimenting on her personal blog and is particularly interested in ethics, IndieWeb, sustainability, privacy, and all things CSS.

Harry Roberts

Harry Roberts is an independent Consultant Web Performance Engineer from the UK. He helps some of the world’s largest and most respected organisations find and fix their site-speed issues.

He is both a Google- and a Cloudinary Media-Developer Expert, and has consulted for clients from the United Nations to the BBC, General Electric to the Financial Times, and a whole host more. He is also co-chair of performance.now(), the web performance conference for professionals.

When not doing client work, he writes, teaches, and speaks about the entire gamut of front-end performance. When not doing work at all, he’s probably out on his bike.

Una Kravets

Una is a Developer Relations Engineer at Google Chrome where she leads the Web UI & DevTools DevRel team. Previously, she was the Director of Product Design at Bustle Digital Group and worked on building maintainable design systems as a UI Engineer at DigitalOcean and IBM. Una is the co-host of the CSS Podcast and Designing in the Browser video series. She has built open source libraries such as CSSgram, spoken at over 80 developer events around the world, and is an avid calligrapher/doodler.

The value pipeline

The CSS spec defines six distinct value stages (declared, cascaded, specified, computed, used, and actual) that every property passes through on its way from a stylesheet to a pixel. We're going to walk you through the pipeline that is used in Ladybird, the independent browser engine we're building from scratch against the web standards.

We'll show you how we pick a winner in the cascade, how we resolve relative units and calc() into absolute values, where layout sneaks back in, and why getComputedStyle() doesn't always return what its name suggests. A peek behind the curtain at the machinery your CSS quietly relies on every day.

Jelle Raaijmakers

Jelle is the COO of the Ladybird Browser Initiative, a San Francisco based non-profit operating on donations and sponsorships. He has been involved with the SerenityOS project since 2021, which gave birth to the Ladybird browser. He oversees operations and finances while remaining actively involved in the browser’s development and day-to-day coding.

Forging Our Own Paths

Moving things along a path has historically been a real pain to pull off on the web, requiring a lot of clever hackery and often a framework or two. Not any more! With some widely available CSS properties melded with some SVG features, we can move pieces of our designs a lot further and more easily than ever before. In this talk, we’ll get down in the weeds of detail and walk together along a path of style, shapes, whimsy, and maybe -- just maybe -- a bit of wonder.

Eric Meyer

Eric has been a burger flipper, a college webmaster, an early blogger, one of the original CSS Samurai, a member of the CSS Working Group, a consultant and trainer, and a Standards Evangelist for Netscape; currently, he is a Developer Advocate at Igalia. Among other things, Eric co-wrote Design For Real Life with Sara Wachter-Boettcher for A Book Apart and CSS: The Definitive Guide with Estelle Weyl for O’Reilly, created the first official W3C test suite, and assisted in the creation of microformats. Eric lives with his family in Cleveland, Ohio, which is a much nicer city than you’ve probably heard. He enjoys a good meal whenever he can and considers almost every form of music to be worthwhile.

Contextualism

How a web page is the most adaptive and advanced user experience in the world, thanks to CSS.

This presentation will be a fun rollup of things like container queries, scroll queries, quantity queries, media queries, anchor queries, selector hacks, user preferences, distance from other elements, and allll that, rolled into a theme of enhancing content to context, using all the ways CSS can help.

Adam Argyle

Adam is a bright, passionate, punk engineer with an adoration for the web who prefers using his skills for best in class UI/UX and empowering those around him. He’s worked at small and large companies, and built an app for pretty much every screen (or voice). He is capable of over-engineering, but spends lots of brain power not to. Loves CSS, loves JS, loves great UX.

What the color?!

If modern CSS color has ever made you go “What the color?!” — you’re not alone.

You have probably wondered if these fancy-schmanzy CSS color things have any value for your work — and every time you tried to understand more, you got dizzy. 😵‍💫

Or maybe you’ve already tried them ... and things got weird. You made a color lighter, but it didn’t look right. You mixed two colors, but got mud. You tried to improve your gradients, but ended up with colors you didn’t ask for.

This talk focuses on how new CSS color features can help you with everyday color tasks, where they fall short and why, what we can do today to work around the issues, what's around the corner, and how YOU can help it get here faster. You’ll pick up a couple of color science concepts along the way — but don’t worry, this is not an academic talk.

“What the color?!” It’s not you.

Lea Verou

Lea has been improving the Web for nearly two decades. In her 14 years in the CSS WG, she designed many features you use daily. As a twice elected W3C TAG member, she helped document the Web’s Design Principles. She is also a TC39 delegate, and a WHATWG contributor. In 2025, she was awarded Pathfinder for Standards by the OpenJS Foundation, for her overall work and impact.

Lea is passionate about making complex concepts approachable, through her talks, books, and open source work. She holds a PhD from MIT, where she spent a decade researching and teaching at the intersection of usability, design, and web technologies.

She lives in Cambridge, Massachusetts and works as an independent consultant with clients ranging from startups to some of the world’s most recognized companies.

Fun with grid lanes

The early web was a playground. We hacked table layouts, sliced images, and spent hours on rounded corners. The tools were limited, but we made things anyway, and constraints fueled our creativity.

That spirit still matters. CSS has grown into something really powerful, and one of the features I'm most excited about is grid-lanes, aka CSS masonry. In this talk, we'll go deep into grid-lanes: how it works, how it differs from grid, what it can and can't do, and how to use it in practice. We'll also go through a series of creative demos that push grid-lanes and other modern CSS features in ways they probably weren't designed for. Bot only because it's fun, but because that's how we best learn and that's how we push against constraints that make the platform better for everyone.

Patrick Brosset

Patrick has been working with web technologies for over 2 decades. He has built websites and apps, libraries and open-source frameworks, and has worked on both Firefox and Chromium DevTools.

Patrick currently works at Microsoft as a developer relations PM on the Microsoft Edge team. He is passionate about the web platform, PWA, and DevTools, and writes a lot of articles about it at on his blog, CSS-Tricks, Smashing Magazine, and others.

CSS Doom Lasers

Let’s take CSS where it has not gone before. Join Niels on a journey through some truly out-there Web experiments, from creating animations and games with CSS and SVG on an 1980s oscilloscope to fully recreating the classic game DOOM in modern CSS. And where will we end up? Perhaps a game of Chrome's offline dinosaur, beamed onto a laser projector.

Niels Leenheer

Niels is a self-professed browser geek. Back in the day, he created HTML5test, and loves the web platform and standards. He has a huge collection of weird devices with even stranger browsers. Recently, he recreated Doom with CSS 3D transforms and animations. He also created a CSS-powered flamethrower, which he is legally prohibited from demonstrating under city ordinances. For his day job, he is CTO of Salonhub and creates web applications for hair salons.

Breaking with habits

Some new features in CSS only show their real potential when we radically break with old habits. Doing that on an existing website is almost impossible. That's why Manuel built a new project from scratch with modern CSS and questioned every line of code he wrote.

In this talk, he presents what he has learned and encourages you to review your best practices.

Manuel Matuzović

Manuel is a freelance frontend developer, accessibility auditor, teacher, author, and consultant who’s passionate about the web. He writes about accessibility, HTML, and CSS on his personal blog matuzo.at and on htmhell.dev.

Color-Scheming

Color-scheme and related color functions have now been around for long enough to really simplify offering multiple themes.

We'll go through why we should do so, what we can use comfortably now, what might still be a bit early for prod, and what's coming soon.

Sara Joy

Sara has been extremely online since 1998, making her own personal websites since 1999. She fell off the wagon some time around 2010, until getting back on it in 2021 to switch her career from electronic engineering to front end web development. She loves the web platform, and wants it to be accessible to everyone.

CSS is eating JavaScript

Modern CSS is quietly absorbing responsibilities that once belonged exclusively to JavaScript. New features like advanced attr(), style queries, and if() open the doors for a complete change in the relationship between CSS and JS.

Thanks to these features CSS can now read and interpret values directly, moving us toward a cleaner separation where JavaScript simply fetches the data and passes the relevant parts to CSS, which can now handle the parsing and logic.

This talk explores what that handoff looks like in practice, the patterns it unlocks, and what it means for how we think about the boundary between styling and scripting.

Kevin Powell

Kevin is a CSS evangelist and educator whose primary goal is to help people fall in love with CSS and, failing that, to at least help them be a little less frustrated by it. He is best known for his YouTube channel, where he posts weekly educational videos that, he hopes, help both inspire and empower people to improve at CSS.

Bruce Lawson: MC

A veteran of the browser wars, many a standards skirmish and an accessibility apocalypse or two, Bruce now leverages synergies for Vivaldi browser.

When web standards finally makes him a billionaire, Bruce has no plans to go to Mars, but will continue making music with the cruellest months.