The :default CSS pseudo-class selects form elements that are the default in a group of related elements.

What this selector matches is defined in HTML Standard §4.16.3 Pseudo-classes — it may match the <button>, <input type="checkbox">, <input type="radio">, and <option> elements:

  • A default option element is the first one with the selected attribute, or the first enabled option in DOM order. multiple <select>s can have more than one selected option, so all will match :default.
  • <input type="checkbox"> and <input type="radio"> match if they have the checked attribute.
  • <button> matches if it is a <form>’s default submission button: the first <button> in DOM order that belongs to the form. (This also applies to <input> types that submit forms, like image or submit.)





  <legend>Favorite season</legend>

  <input type="radio" name="season" id="spring">
  <label for="spring">Spring</label>

  <input type="radio" name="season" id="summer" checked>
  <label for="summer">Summer</label>

  <input type="radio" name="season" id="fall">
  <label for="fall">Fall</label>

  <input type="radio" name="season" id="winter">
  <label for="winter">Winter</label>


input:default {
  box-shadow: 0 0 2px 1px coral;

input:default + label {
  color: coral;



Specification Status Comment
HTML Living Standard
The definition of ':default' in that specification.
Living Standard No change.
The definition of ':default' in that specification.
Recommendation Defines associated HTML semantics and constraint validation.
Selectors Level 4
The definition of ':default' in that specification.
Working Draft No change.
CSS Basic User Interface Module Level 3
The definition of ':default' in that specification.
Recommendation Initial definition, but without the associated semantics.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
:defaultChrome Full support 10Edge ? Firefox Full support 4IE No support NoOpera Full support 10Safari Full support 5WebView Android Full support 37Chrome Android Full support 18Edge Mobile ? Firefox Android Full support 4Opera Android Full support 10.1Safari iOS Full support 5Samsung Internet Android ?


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