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::before pseudo-element

Defines generated content that appears before an element.

Syntax

sel::before {...}

Parameters

sel: A simple selector.

Standards information

CSS 2.1, Section 5.12.3

Remarks

The ::before and ::after pseudo-elements specify the location of content before and after an element in the document tree. The content attribute, in conjunction with these pseudo-elements, specifies what is inserted. Other specified styling properties apply to the appearance of the inserted content, not to the element's content.

The generated content interacts with other boxes as if they were real elements inserted just inside their associated element. The content box of the associated element expands to include the generated content, if necessary.

In Windows Internet Explorer 8, as well as later versions of Windows Internet Explorer in IE8 Standards mode, only the one-colon form of this pseudo-element is recognized—that is, :before.

Beginning with Windows Internet Explorer 9, the ::before pseudo-element requires two colons, though the one-colon form is still recognized and behaves identically to the two-colon form. Microsoft and the World Wide Web Consortium (W3C) encourage web authors to use the two-colon form of the ::before pseudo-element. For more information, see the Pseudo-elements section of the W3C's CSS3 Selectors specification.

Examples

The following rule inserts the string "Note: " before the content of every p element whose CLASS attribute has the value "note". The "Note: " string will be displayed in brown on a yellow background with a blue border; the element itself will remain unchanged.

CSS


p.note::before { 
  content: "Note: " 
  color: brown;
  background: yellow;
  border: 1px solid blue;
}

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