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:required

The :required CSS pseudo-class represents any <input>, <select>, or <textarea> element that has the required attribute set on it.

Try it

This pseudo-class is useful for highlighting fields that must have valid data before a form can be submitted.

Note: The :optional pseudo-class selects optional form fields.

Syntax

:required {
  /* ... */
}

Examples

The required field has a red border

HTML

<form>
  <div class="field">
    <label for="url_input">Enter a URL:</label>
    <input type="url" id="url_input" />
  </div>

  <div class="field">
    <label for="email_input">Enter an email address:</label>
    <input type="email" id="email_input" required />
  </div>
</form>

CSS

label {
  display: block;
  margin: 1px;
  padding: 1px;
}

.field {
  margin: 1px;
  padding: 1px;
}

input:required {
  border-color: #800000;
  border-width: 3px;
}

input:required:invalid {
  border-color: #c00000;
}

Result

Accessibility concerns

Mandatory <input>s should have the required attribute applied to them. This will ensure that people navigating with the aid of assistive technology such as a screen reader will be able to understand which inputs need valid content to ensure a successful submission.

If the form also contains optional inputs, required inputs should be indicated visually using a treatment that does not rely solely on color to convey meaning. Typically, descriptive text and/or an icon are used.

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
:required 10 12 4 10 10 5 4.4.3 18 4 10.1 5 1.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/CSS/:required