Steps to replicate the issue (include links if applicable):

• Tried saving "aspect-ratio: 1.5;" in https://meta.wikimedia.org/wiki/Template:Wiki_Loves_Living_Heritage/style.css

What happens?:
The editor responds: "Unrecognized or unsupported property at line 98 character 2." and refuses to save.

What should have happened instead?:
File saved

Other information (browser name/version, screenshots, etc.):
Known problem, requesting to update the allowed properties