What is a pseudo element?

Question

I'm dissecting this very beautiful example of how CSS can help you create nice glow effects on images.

This particular line from the example mentions:

Although this method will only produce the full effect in Firefox 4, other browsers will eventually catch up and apply transitions to pseudo-elements.

What is a pseudo-element?

"What is a pseudo element?" [answers](http://bit.ly/19BalsR) — Barnee, Aug 02 '13 at 06:50
Also worth knowing - [What is the difference between a pseudo-class and a pseudo-element in CSS?](https://stackoverflow.com/q/8069973/465053) — RBT, Jan 10 '19 at 06:36

score 10 · Accepted Answer · edited Dec 11 '11 at 18:04

Pseudo-elements are CSS selectors that manipulate parts of an element in a special way.

They include:

:first-line
:before
:after

Application

Pseudo elements are applied like so

p:first-letter{
    color:black;
    font-style:italic;
}

Note: the : followed by the selector is how pseudo elements are denoted in CSS1 and CSS2. In CSS3, the double colon is used (::) to distinguish them from pseudo-classes.

More details here: http://reference.sitepoint.com/css/pseudoelements

Support

Support is decent for a number of browsers, with older versions of IE notably poor with support. QuirksMode has a compatibility table (a bit out-of-date but still useful): http://www.quirksmode.org/css/contents.html#t15

Cool Tricks

Pseudo elements can do some cool things, including

show the URLs of links in printed docs
fake a float:center;

See more here: http://css-tricks.com/9516-pseudo-element-roundup/

With jQuery

jQuery has a number of unique selectors that enhance and expand on the native CSS group:

http://api.jquery.com/category/selectors/

Note: you can use jQuery to force older browsers to adopt certain rules. For example, IE6 will ignore :last-child. Using jQuery can force IE6 to apply that style.

The Spec

http://www.w3.org/TR/CSS2/selector.html#pseudo-element-selectors

Note that the `:hover` selector can also be used with other elements. — ComFreek, Oct 13 '11 at 17:31
`:first-child` is also a pseudo-class, not a pseudo-element - I've edited that out for you. Nice answer by the way :) — BoltClock, Dec 11 '11 at 18:04

score 2 · Answer 2 · answered Oct 13 '11 at 17:26

2

Its not an element in the dom. Its something you can select with a selector, notably after a :.

http://www.htmldog.com/guides/cssadvanced/pseudoelements/

answered Oct 13 '11 at 17:26

Daniel A. White

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