The CSS Cascade: A Deep Dive (2022.06.09 @ CSS Day)

Written by / Original link on Jun. 28, 2022


On June 9 & 10, I was in Amsterdam for CSS Day – a conference I’ve been attending since it’s very first edition in 2013. This time – after a two year hiatus due to youknowwhat – I was very glad to be back! This time not as an attendee though, but as a speaker. In my talk I covered the details of the CSS Cascade, with a huge focus on CSS Cascade Layers.

CSS is short for Cascading Style Sheets. But what exactly is this Cascade, and how does it work? What are Origins? How do you calculate Specificity? And where do those new Cascade Layers you might have heard of fit in? And oh, what exactly happens when you use an !important somewhere?

In this insightful talk, we’ll take a look under the hood of browsers, and detail how they determine which CSS declarations to apply and which not.

The slides are up on, and also embedded below:

[Check slides on]

The talk was recorded and will premiere on the CSS Day YouTube Channel on July 7 at 13:55. This recording might be of more help, as the slides themselves lack some explanation and supporting animations to tell the whole story.

☝️ If you’re looking a full content-recap of CSS Day, I would recommend the recaps by Grrr:


Elad, Amit, Adam, Hui Jing, and me

It felt great to be back on stage speaking to a real crowd again. There’s a great vibe going on during the conference, speaker dinner, and hallway track that simply cannot be matched by any virtual event. Meeting some CSS friends who I only know through Twitter in real life for the very first time, as well as meeting new people, and hanging out with some of my Google colleagues (who I, as a remote worker, normally only get to see through a screen), is an enriching experience.



I would like to thank organizers Krijn and PPK for having me. Having organised events for almost a decade now, they know how to do it – even a totally new venue was no hurdle to them.

A big thanks to the other speakers as well for giving their talks – the quality, as per usual, was very high level. I’m honored to have been part of this stellar line-up, and hope I was able to meet the same level of quality.

I hope you all had fun attending my talk — I know I had making it (and whilst bringing it forward) — and perhaps you even learned something from it along the way 🙂


💁‍♂️ If you are a conference or meetup organiser, don't hesitate to contact me to come speak at your event.

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