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This post is part of my Today I learned series in which I share all my web development learnings.

I'm following the project on GitHub which means I get notifications about additions to the web platform and updated browser support. Today, I stumbled upon an issue including new CSS Level 4 selectors that are or will be included on

It turns out there are a lot of new selectors on their way, and one interesting one is a flag which makes attribute selectors case-insensitive.

 * matches:
 * <div class="foo">...</div>
 * <div class="Foo">...</div>
 * <div class="fOo">...</div>
 * ...
[class=foo i] {
  color: red;

The browser support's looking good as well.

If you want to play around with it, I created a quick codepen. The only case I can think of this being useful is when you have to deal with user-generated content, and the possibility is quite high the users enter not accurate data. I would love to learn more about other use cases – if you have an idea, please let me know!

Edited: Dominik pointed out that this could be indeed useful for user-generated content in input fields using the value attribute.

 * matches:
 * <input value="hello world">
 * <input value="hello World">
 * <input value="hElLo WoRlD">
 * ...
[value="hello world" i] { /* ... */ }
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Stefan standing in the park in front of a green background

Frontend nerd with over ten years of experience, "Today I Learned" blogger, conference speaker, Tiny helpers maintainer, and DevRel at Checkly.