Serving a very similar role to Salesforce&#x27;s Lightning Design System: <a href="http:&#x2F;&#x2F;www.lightningdesignsystem.com&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.lightningdesignsystem.com&#x2F;</a>. Build your extension in the native UI, but go ahead and use it anywhere if you want.