The :only-child CSS pseudo-class represents an element without any siblings. This is the same as :first-child:last-child or :nth-child(1):nth-last-child(1), but with a lower specificity.
/* Selects each <p>, but only if it is the */
/* only child of its parent */
p:only-child {
  background-color: lime;
}
Note: As originally defined, the selected element had to have a parent. Beginning with Selectors Level 4, this is no longer required.
Syntax
:only-child
Examples
Basic example
HTML
<main>
  <div>
    <i>I am a lonely only child.</i>
  </div>
  <div>
    <i>I have siblings.</i><br>
    <b>So do I!</b><br>
    <span>I also have siblings, <span>but this is an only child.</span></span>
  </div>
</main>
CSS
main :only-child {
  color: red;
}
Result
A list example
HTML
<ol>
  <li>First
    <ul>
      <li>This list has just one element.
    </ul>
  </li>
  <li>Second
    <ul>
      <li>This list has three elements.
      <li>This list has three elements.
      <li>This list has three elements.
    </ul>
  </li>
<ol>
CSS
li li {
  list-style-type: disc;
}
li:only-child {
  color: red;
  list-style-type: square;
}
Result
Specifications
| Specification | Status | Comment | 
|---|---|---|
| Selectors Level 4 The definition of ':only-child' in that specification. | Working Draft | Matching elements are not required to have a parent. | 
| Selectors Level 3 The definition of ':only-child' in that specification. | Recommendation | Initial definition. | 
Browser compatibility
| Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari | 
|---|---|---|---|---|---|---|
| Basic support | 2 | (Yes) | 1.5 (1.8) | 9 | 9.5 | 3.1 | 
| No parent required | 57 | ? | ? | ? | 44 | ? | 
| Feature | Android Webview | Chrome for Android | Edge | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile | 
|---|---|---|---|---|---|---|---|
| Basic support | (Yes) | (Yes) | (Yes) | 1.0 (1.8) | 9 | 10 | 3.1 | 
| No parent required | 57 | 57 | ? | ? | ? | 44 | ? | 
See also
Document Tags and Contributors
    
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                       Last updated by:
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