Comment by Aardwolf

Thanks, seems to work at first sight in combination with text-align for the horizontal alignment!

That means I may finally not need line-height or multi-element tricks for this anymore

Interesting that this is finally there since a year!

I wonder what made them decide to support it finally, since CSS's creation in 1996.

A button never looks professional if the text in it isn't centered, this was a really needed feature and I still can't understand why it took that long

Edit: it does seem worrying that for me this property vertically centers but not horizontally while the description of it doesn't say vertical but is: "The items are packed flush to each other in the center of the alignment container along the cross axis."