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

• I want to use aspect-ratio css tags in my templatestyles, but it is blocklisted
• I have come across several other definitions that I cannot use as well

What happens?:

• The stylesheet cannot be saved

What should have happened instead?:

• Saving the stylesheet

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.):