:default - CSS: Cascading Style Sheets 编辑

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.

Syntax

:default

Examples

HTML

<fieldset>
  <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>
</fieldset>

CSS

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

input:default + label {
  color: coral;
}

Result

Specifications

BCD tables only load in the browser

• Web forms — Working with user data
• Styling web forms
• Related HTML elements: <button>, <input type="checkbox">, <input type="radio">, and <option>