#CSS Shadow Parts brings a new CSS selector (::part()) to enable stylistic customization of Web components: #WebComponents creators get to identify which part of the Shadow DOM they create can have their style customized in the hosting page. w3.org/TR/css-shadow-parts-1…

For instance, an <hello-wolrd> component defined with <template>Hello <span part=name>World</span></template> could be styled in a page using the compenent with hello-world::part(name) { color: red;}