Let web.extensions add userChrome.css

[Vockster]

I would like web extensions to be able to modify the chrome.css and the firefox API. I came from OperaGX and I really enjoyed the thin side bars and workspaces. I am trying to make an extension to copy that but 9 times out of 10 I find that the firefox API gets in the way on things I want to customize and the only way to fix it is a userChrome.css file change, but that cannot be shipped seamlessly. I want my extension to be plug and play and user friendly, but without web extensions having access to the userChrome.css it gets difficult. 

[Jon]

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[grundt]

This is a great idea ... if Theme developers could actually make more substantive UI alterations there might not be so much angst over imposed UI redesigns