Try it

label {
  display: block;
  margin-top: 1em;
}
.req {
  color: red;
}
*:optional {
  background-color: palegreen;
}

<form>
  <label for="name">Name: <span class="req">*</span></label>
  <input id="name" name="name" type="text" required />
  <label for="birth">Date of Birth:</label>
  <input id="birth" name="birth" type="date" />
  <label for="origin"
    >How did you find out about us? <span class="req">*</span></label
  >
  <select id="origin" name="origin" required>
    <option>Google</option>
    <option>Facebook</option>
    <option>Advertisement</option>
  </select>
  <p><span class="req">*</span> - Required field</p>
</form>

This pseudo-class is useful for styling fields that are not required to submit a form.

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

Syntax

css

:optional {
  /* ... */
}

If a form contains optional <input>s, required inputs should be indicated using the required attribute. 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 form submission.

Required inputs should also 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.

Examples

The optional field has a purple border

HTML

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

css

label {
  display: block;
  margin: 1px;
  padding: 1px;
}
.field {
  margin: 1px;
  padding: 1px;
}
input:optional {
  border-color: rebeccapurple;
  border-width: 3px;
}

Result

Specifications

Specification
HTML # selector-optional
Selectors Level 4 # optional-pseudo

Browser compatibility

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This page was last modified on Apr 17, 2026 by MDN contributors.