It used to be possible to write "shadow-piercing" CSS selectors, but this capability was removed for making it too easy to violate the encapsulation. (And indee

It used to be possible to write "shadow-piercing" CSS selectors, but this capability was removed for making it too easy to violate the encapsulation. (And indeed, I saw it frequently used to accommodate misuse of the Shadow DOM API.) https://developers.google.com/web/updates/2017/10/remove-shadow-piercing https://developers.google.com/web/updates/2017/10/remove-sha... It sounds like "Shadow Parts" will let you target subcomponents in some Shadow DOMs, once it's implemented, but I'm afraid that's probably not going to help you with misbehaving websites.