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Kevin Powell @kevinpowell.co · 06/08/2026

When I collected answers on people's favourite colour format for @asked100devs.bsky.social, with the people who said rgb, there were more people who put rgba() instead of rgb()... So, quick PSA: we haven't needed the 'a' for a very, very long time.

a selector with a class of "these are the same", and then two color declarations. The first one uses an rgba function, the second an rgb function, both with all the color values at 0, and the alpha value at .5

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Kevin Powell @kevinpowell.co · 06/08/2026

And if you're dropping the a, you might as well go space-separated, since the new color functions use that, and support is great. Oh, and relative colors use it too! I wrote about all of this over on @piccalil.li a little while back if you want to learn more: piccalil.li/blog/a-pragm...

three examples of the rgb function in CSS, first the rgba, then rgb with commas, and finally an rgb function using the space-separated syntax.

Then a second set of color functions, with hwb(), oklch(), and color(), all which can only use the space-separated syntax.

root selector has a custom property that has a color value, and then there is a selector delcaring a color, using a relative color to lower the opacity of the custom properties color.

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