::before

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

In CSS, ::before creates a pseudo-element that is the first child of the selected element. It is often used to add cosmetic content to an element with the content property. It is inline by default.

Try it

a {
  color: #0000ff;
  text-decoration: none;
}

a::before {
  content: "🔗";
}

.local-link::before {
  content: url("/shared-assets/images/examples/firefox-logo.svg");
  display: inline-block;
  width: 15px;
  height: 15px;
  margin-right: 5px;
}

<p>
  Learning resources for web developers can be found all over the internet. Try
  out
  <a href="https://web.dev/">web.dev</a>,
  <a href="https://www.w3schools.com/">w3schools.com</a> or our
  <a href="https://developer.mozilla.org/" class="local-link">MDN web docs</a>.
</p>

Syntax

css
::before {
  content: /* value */;
  /* properties */
}

Description

The ::before pseudo-element is an inline box generated as an immediate child of the element it is associated with, or the "originating element". It is often used to add cosmetic content to an element via the content property, such as icons, quote marks, or other decoration.

::before pseudo-elements can't be applied to replaced elements such as <img>, whose contents are determined by external resources and not affected by the current document's styles.

A ::before pseudo-element with a display value of list-item behaves like a list item, and can therefore generate a ::marker pseudo-element just like an <li> element.

If the content property is not specified, has an invalid value, or has normal or none as a value, then the ::before pseudo-element is not rendered. It behaves as if display: none is set.

Note: The Selectors Level 3 specification introduced the double-colon notation ::before to distinguish pseudo-classes from pseudo-elements. Browsers also accept single-colon notation :before, introduced in CSS2.

Accessibility

Using a ::before pseudo-element to add content is discouraged, as it is not reliably accessible to screen readers.

Examples

Quotation marks

One example of using ::before pseudo-elements is to provide quotation marks. Here we use both ::before and ::after to insert quotation characters.

HTML

html
<q>Some quotes</q>, he said, <q>are better than none.</q>

CSS

css
q::before {
  content: "«";
  color: blue;
}

q::after {
  content: "»";
  color: red;
}

Result

Decorative example

We can style text or images in the content property almost any way we want.

HTML

html
<span class="ribbon">Notice where the orange box is.</span>

CSS

css
.ribbon {
  background-color: #5bc8f7;
}

.ribbon::before {
  content: "Look at this orange box.";
  background-color: #ffba10;
  border-color: black;
  border-style: dotted;
}

Result

To-do list

In this example we will create a to-do list using pseudo-elements. This method can often be used to add small touches to the UI and improve user experience.

HTML

html
<ul>
  <li>Buy milk</li>
  <li>Take the dog for a walk</li>
  <li>Exercise</li>
  <li>Write code</li>
  <li>Play music</li>
  <li>Relax</li>
</ul>

CSS

css
li {
  list-style-type: none;
  position: relative;
  margin: 2px;
  padding: 0.5em 0.5em 0.5em 2em;
  background: lightgrey;
  font-family: sans-serif;
}

li.done {
  background: #ccff99;
}

li.done::before {
  content: "";
  position: absolute;
  border-color: #009933;
  border-style: solid;
  border-width: 0 0.3em 0.25em 0;
  height: 1em;
  top: 1.3em;
  left: 0.6em;
  margin-top: -1em;
  transform: rotate(45deg);
  width: 0.5em;
}

JavaScript

js
const list = document.querySelector("ul");
list.addEventListener(
  "click",
  (ev) => {
    if (ev.target.tagName === "LI") {
      ev.target.classList.toggle("done");
    }
  },
  false,
);

Here is the above code example running live. Note that there are no icons used, and the check-mark is actually the ::before that has been styled in CSS. Go ahead and get some stuff done.

Result

Unicode escape sequences

As generated content is CSS, not HTML, you can't use markup entities in content values. If you need to use a special character, and can't enter it literally into your CSS content string, use a unicode escape sequence. This consists of a backslash followed by the character's hexadecimal unicode value.

HTML

html
<ol>
  <li>Crack Eggs into bowl</li>
  <li>Add Milk</li>
  <li>Add Flour</li>
  <li aria-current="step">Mix thoroughly into a smooth batter</li>
  <li>Pour a ladleful of batter onto a hot, greased, flat frying pan</li>
  <li>Fry until the top of the pancake loses its gloss</li>
  <li>Flip it over and fry for a couple more minutes</li>
  <li>serve with your favorite topping</li>
</ol>

CSS

css
li {
  padding: 0.5em;
}

li[aria-current="step"] {
  font-weight: bold;
}

li[aria-current="step"]::before {
  content: "\21E8 "; /* Unicode escape sequence for "Rightwards White Arrow" */
  display: inline;
}

Result

::before::marker nested pseudo-elements

The ::before::marker nested pseudo-element selects the list ::marker of an ::after pseudo-element that is itself a list item, that is, it has its display property set to list-item.

In this demo, we generate extra list items before and after a list navigation menu using ::before and ::after (setting them to display: list-item so they behave like list items). We then use ul::before::marker and ul::after::marker to give their list markers a different color.

HTML

html
<ul>
  <li><a href="#">Introduction</a></li>
  <li><a href="#">Getting started</a></li>
  <li><a href="#">Understanding the basics</a></li>
</ul>

CSS

css
ul {
  font-size: 1.5rem;
  font-family: Arial, Helvetica, sans-serif;
}

ul::before,
ul::after {
  display: list-item;
  color: orange;
}

ul::before {
  content: "Start";
}

ul::after {
  content: "End";
}

ul::before::marker,
ul::after::marker {
  color: red;
}

Result

While the list bullets of the three navigation items are generated because they are <li> elements, "Start" and "End" have been inserted via pseudo-elements and ::marker is used to style their bullets.

Specifications

Specification
CSS Pseudo-Elements Module Level 4
# generated-content

Browser compatibility

See also