Brecht De Ruyte

Fourteen talks, two days, one city. Color spaces, a browser built from scratch, CSS that runs x86 machine code, a select that took 33 years, and a masonry layout that is finally real. This was CSS Day 2026.

It’s been a few years since the Interop initiative was set in play. This has historically been one of the key elements in moving the web forward as it aims for a consistent web between browser vendors. In contrast to the “old days browser wars”, we as developers get streamlined features without having to check everything in every browser. The features of Interop 2025 are now known, features to be made stable across browsers by the end of the year. In this article, we’ll take a look at what we should get acquainted with in 2025.

Another year, another CSS Day. I’m always happy to return to Amsterdam for this occasion, It’s one of the things I look forward to every year. So naturally, I’m happy that iO still allowed me to go there with my training budget, and the least I could do, is write a summary of this event on the tech_hub.

Oh my, usually when writing a series like this, people tend to leave the best for last, but in this case, it seems that the best is behind us. But as I am a completionist, this last part of the CSS Units series will be about absolute units, the units you mostly - absolutely - want to avoid. But can help in certain cases.

In the third part of this series, we’ll look at length units based on the container. Yes, you heard that right, we can finally get some measurements based on a containing element and that just spells awesome in my book. Currently available in all evergreen browsers, these units open up a lot of opportunities to create some smart systems and once again, I will write this up packed with a bunch of demos and cool use cases.

In this second part of the series, let’s talk about units based on the viewport also known as "the viewport-percentage length units". A lot of developers know these, but they can create some unexpected behavior, especially in combination with scrollbars and mobile behavior. Based on some articles and videos I picked up on the web from time to time, I'd like to explain some of the common pitfalls when using viewport units.

There are a lot of CSS units available at the moment and we mostly still rely on pixels and (r)ems for our sizing and fonts. I say it’s time to do a little freshening up. Instead of writing a list of which units are available in CSS that you can easily find on MDN as well, I thought I’d give some examples of where they could come in handy. I will create a mini-series out of this and for the first part, let’s start off with relative length units based on font.

If you love CSS, you’ve probably heard of custom properties (a.k.a. CSS variables) before. Still, a lot of people seem to use them as constants for their CSS. In this article, I will try to give you some more insights on how you can use these custom properties to create some smart systems or even use them as booleans in CSS and create easy progressive enhancements.

In the previous part of this article, I tried to tickle your brain a bit to unleash your curiosity and drive your determination to try some new CSS features today. That's exactly what I'll be doing in this part, writing some new stuff today so you can slowly polish new CSS skills very sneaky and hidden in the code, like a ninja.

Unless you have no affinity with CSS at all or have been living under a rock for the last year, you should have noticed that new CSS features are skyrocketing like never before. Although this is a good thing, it might get frustrating to get a grasp on all these new playthings because every time you add something new in your styling toolbox, the next best thing is just around the corner.

The :has() relational pseudo class has landed in Chrome and Safari and even though it gets less hype than for instance container queries, I believe this little pseudo class contains a lot of improvements to the way we write CSS today.

After a long break because of Covid-19, CSS Day is back. In a new location at the Zuiderkerk in Amsterdam. Once again trying to create the perfect line-up for everything design and CSS, and boy, they delivered just that.

How should scroll snapping tabs behave when using keys? By reading some best practices, I believe I found an elegant solution.