Consider using adoptedStyleSheets for injecting stylesheets

[infmagic2047]

It has been known for a long time that qutebrowser's current method of injecting stylesheets breaks on sites with strict Content Security Policy (#7498, #7342). Looking at how Stylus does this now (https://github.com/openstyles/stylus/blob/671c012c3d6eac770d4bfc8830a6f3b31ad08232/content/style-injector.js), they are using document.adoptedStyleSheets as an alternative method.

I can verify that adoptedStyleSheets works for sites with strict CSP. It can be a good idea to use it as a fallback when the old method does not work, or maybe just drop the old method and use it everywhere - I am not aware of any downsides of the adoptedStyleSheets way, but I am not a web dev so I may be missing something.

[The-Compiler]

Oh, interesting find for sure, I wasn't aware of this!

@ulrikdem if you still use qutebrowser, and have the time, this might be one for you to look at?

[ulrikdem]

Sorry, I am not currently using qutebrowser, and don't have the time to look into this.