Shadow DOM isn't a totally sandboxed construct, though it mostly is. You can't load font-face's within shadow dom's. They have to be defined in light dom, and t

Shadow DOM isn't a totally sandboxed construct, though it mostly is. You can't load font-face's within shadow dom's. They have to be defined in light dom, and then are available in shadow dom. Most other CSS styling seems to be totally isolated, given this exception. It appears custom CSS properties pierce through as well. https://open-wc.org/guides/knowledge/styling/styles-piercing-shadow-dom/ https://open-wc.org/guides/knowledge/styling/styles-piercing...