:indeterminate

The :indeterminate CSS pseudo-class represents any form element whose state is indeterminate, such as checkboxes which have their HTML indeterminate attribute set to true, radio buttons which are members of a group in which all radio buttons are unchecked, and indeterminate <progress> elements.

/* Selects any <input> whose state is indeterminate */
input:indeterminate {
  background: lime;
}

Elements targeted by this selector are:

• <input type="checkbox"> elements whose indeterminate property is set to true by JavaScript
• <input type="radio"> elements, when all radio buttons with the same name value in the form are unchecked
• <progress> elements in an indeterminate state

:indeterminate

This example applies special styles to the labels associated with indeterminate form fields.

HTML

<div>
  <input type="checkbox" id="checkbox">
  <label for="checkbox">This label starts out lime.</label>
</div>
<div>
  <input type="radio" id="radio">
  <label for="radio">This label starts out lime.</label>
</div>

CSS

input:indeterminate + label {
  background: lime;
}

JavaScript

var inputs = document.getElementsByTagName("input");

for (var i = 0; i < inputs.length; i++) {
  inputs[i].indeterminate = true;
}

HTML

<progress>

CSS

progress {
  margin: 4px;
}

progress:indeterminate {
  opacity: 0.5;
  background-color: lightgray;
  box-shadow: 0 0 2px 1px red;
}