The :host
CSS pseudo-class selects the shadow host of the shadow DOM containing the CSS it is used inside — in other words, this allows you to select a custom element from inside its shadow DOM.
Note: This has no effect when used outside a shadow DOM.
/* Selects a shadow root host */ :host { font-weight: bold; }
Syntax
:host
Examples
Styling the shadow host
The following snippets are taken from our host-selectors example (see it live also).
In this example we have a simple custom element — <context-span>
— that you can wrap around text:
<h1>Host selectors <a href="#"><context-span>example</context-span></a></h1>
Inside the element's constructor, we create style
and span
elements, fill the span
with the content of the custom element, and fill the style
element with some CSS rules:
let style = document.createElement('style'); let span = document.createElement('span'); span.textContent = this.textContent; const shadowRoot = this.attachShadow({mode: 'open'}); shadowRoot.appendChild(style); shadowRoot.appendChild(span); style.textContent = 'span:hover { text-decoration: underline; }' + ':host-context(h1) { font-style: italic; }' + ':host-context(h1):after { content: " - no links in headers!" }' + ':host-context(article, aside) { color: gray; }' + ':host(.footer) { color : red; }' + ':host { background: rgba(0,0,0,0.1); padding: 2px 5px; }';
The :host { background: rgba(0,0,0,0.1); padding: 2px 5px; }
rule styles all instances of the <context-span>
element (the shadow host in this instance) in the document.
Specifications
Specification | Status | Comment |
---|---|---|
CSS Scoping Module Level 1 The definition of ':host' in that specification. |
Working Draft | Initial definition. |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
:host | Chrome Full support 54 | Edge Full support 79 | Firefox
Full support
63
| IE No support No | Opera Full support 41 | Safari Full support 10 | WebView Android Full support 54 | Chrome Android Full support 54 | Firefox Android
Full support
63
| Opera Android Full support 41 | Safari iOS Full support 10 | Samsung Internet Android Full support 6.0 |
Legend
- Full support
- Full support
- No support
- No support
- User must explicitly enable this feature.
- User must explicitly enable this feature.