<h1>MDN Web Docs Demo: :fullscreen pseudo-class</h1>  <p>This demo uses the <code>:fullscreen</code> pseudo-class to automatically   change the style of a button used to toggle fullscreen mode on and off,   entirely using CSS.</p>  <button id="fs-toggle">Toggle Fullscreen</button> 

:fullscreen

The :fullscreen CSS pseudo-class matches every element which is currently in fullscreen mode. If multiple elements have been put into fullscreen mode, this selects them all.

Syntax

:fullscreen

Usage notes

The :fullscreen pseudo-class lets you configure your stylesheets to automatically adjust the size, style, or layout of content when elements switch back and forth between fullscreen and traditional presentations.

Examples

In this example, the color of a button is changed depending on whether or not the document is in fullscreen mode. This is done without needing to specifically apply style changes using JavaScript.

HTML

The page's HTML looks like this:

<h1>MDN Web Docs Demo: :fullscreen pseudo-class</h1>  <p>This demo uses the <code>:fullscreen</code> pseudo-class to automatically   change the style of a button used to toggle fullscreen mode on and off,   entirely using CSS.</p>  <button id="fs-toggle">Toggle Fullscreen</button> 

The <button> with the ID "fs-toggle" will change between pale red and pale green depending on whether or not the document is in fullscreen mode.

CSS

The magic happens in the CSS. There are two rules here. The first establishes the background color of the "Toggle Fullscreen Mode" button when the element is not in a fullscreen state. The key is the use of the :not(:fullscreen), which looks for the element to not have the :fullscreen pseudo-class applied to it.

#fs-toggle:not(:fullscreen) {   background-color: #afa; } 

When the document is in fullscreen mode, the following CSS applies instead, setting the background color to a pale shade of red.

#fs-toggle:fullscreen {   background-color: #faa; } 

Specifications

See also

Last modified: Feb 15, 2022, by MDN contributors