Several flex and grid CSS properties listed as Unknown property in Customizer

[davidjlaietta]

When I use the CSS editor in the Customizer it suggests element properties as I start typing them. One of the properties that it suggests is the justify-items property. When I save the settings in the Customizer I get a notice of "Unknown property 'justify-items'."

I've checked some of the other flexbox and grid properties, and there are several others that this is the case for, namely:

• justify-items
• grid-gap
• grid-column-gap
• grid-row-gap
• place-self

The properties still work in supported browsers, they just display an error in the Customizer. Some valid values for properties that are recognized also give errors, such as the values of start and end for several grid properties.

[davidjlaietta]

screenshot of Customizer Edit CSS showing an unknown property

[davidjlaietta]

screenshot of Customizer Edit CSS showing the suggestion of an unknown property

[subrataemfluence]

Added property justify-items

[subrataemfluence]

Warning disappeared

[westonruter]

@subrataemfluence Your patch doesn't indicate which file it is that is being patched.

[subrataemfluence]

Oops! I am sorry for this. It's almost midnight here. Will fix the patch tomorrow morning.

Replying to westonruter:

@subrataemfluence Your patch doesn't indicate which file it is that is being patched.

[subrataemfluence]

@westonruter I modified initial patch and uploaded 43896-1.diff. In this patch I considered all properties @davidjlaietta mentioned.

However, this one has some unwanted white spaces and tabs characters, which I realized only after uploading. So, I removed them and uploaded a newer version 43896-2.diff. Hope this works!

[celloexpressions]

This appears to be the same general issue as described in #43197. The fix here is likely a good approach for that ticket as well.

Can those actively working on the latest innovations in CSS please review 43896-2.diff​ and confirm any other properties that should be added to the core list?