In modern browsers that support the Shadow DOM[1] standard, this is a somewhat solved problem with one caveat: it wasn't built for this use case. Architectural

In modern browsers that support the Shadow DOM[1] standard, this is a somewhat solved problem with one caveat: it wasn't built for this use case. Architecturally, however, it does the job but the challenge is integration with dated browsers. Polyfills for Shadow DOM inherently break the security features it provides. Better cross-browser Shadow DOM support would be a step in the right direction to making things like DOMPurify safer, but unfortunately it seems like we're a while away from that according to Can I Use[2]. [1]: https://developer.mozilla.org/en-US/docs/Web/Web_Components/Using_shadow_DOM https://developer.mozilla.org/en-US/docs/Web/Web_Components/... [2]: https://caniuse.com/#feat=shadowdomv1 https://caniuse.com/#feat=shadowdomv1