How To Use Psudeo Classes In CSS?

In this tutorial, you will learn what a pseudo-class is and how you can use them to target different elements on your page.  Using pseudo-classes is a powerful tool in the frontend developer's toolkit to enable cool effects on your webpage, that you may have thought could be achieved using Javascript.

How Do I Target State On A Page In CSS?

When someone visits your web page and performs certain actions, like hovering the mouse over a link, in the background the web browser dynamically applies different 'state'.  This 'state management' is done by the browser by applying something called a pseudo-state to the element.

How the browser applies state is pretty boring, however, as a frontend developer you can use these different states/pseudo-classes to change the style of your elements depending on the state.  In the example above, when you hover your mouse over a link the browser will apply the 'hover' pseudo-class to that link.  You can then write a CSS selector to target the link in hover state to say apply an underline.

Pseudo-classes should hopefully be fairly simple to grasp.  There are loads of pseudo-classes available that allow you to target a whole host of different actions and states.

All CSS Pseudo Classes

Selector Example Example description
:active a:active Selects the active link
:checked input:checked Selects every checked <input> element
:disabled input:disabled Selects every disabled <input> element
:empty p:empty Selects every <p> element that has no children
:enabled input:enabled Selects every enabled <input> element
:first-child p:first-child Selects every <p> elements that is the first child of its parent
:first-of-type p:first-of-type Selects every <p> element that is the first <p> element of its parent
:focus input:focus Selects the <input> element that has focus
:hover a:hover Selects links on mouse over
:in-range input:in-range Selects <input> elements with a value within a specified range
:invalid input:invalid Selects all <input> elements with an invalid value
:lang(language) p:lang(it) Selects every <p> element with a lang attribute value starting with "it"
:last-child p:last-child Selects every <p> elements that is the last child of its parent
:last-of-type p:last-of-type Selects every <p> element that is the last <p> element of its parent
:link a:link Selects all unvisited links
:not(selector) :not(p) Selects every element that is not a <p> element
:nth-child(n) p:nth-child(2) Selects every <p> element that is the second child of its parent
:nth-last-child(n) p:nth-last-child(2) Selects every <p> element that is the second child of its parent, counting from the last child
:nth-last-of-type(n) p:nth-last-of-type(2) Selects every <p> element that is the second <p> element of its parent, counting from the last child
:nth-of-type(n) p:nth-of-type(2) Selects every <p> element that is the second <p> element of its parent
:only-of-type p:only-of-type Selects every <p> element that is the only <p> element of its parent
:only-child p:only-child Selects every <p> element that is the only child of its parent
:optional input:optional Selects <input> elements with no "required" attribute
:out-of-range input:out-of-range Selects <input> elements with a value outside a specified range
:read-only input:read-only Selects <input> elements with a "readonly" attribute specified
:read-write input:read-write Selects <input> elements with no "readonly" attribute
:required input:required Selects <input> elements with a "required" attribute specified
:root root Selects the document's root element
:target #news:target Selects the current active #news element (clicked on a URL containing that anchor name)
:valid input:valid Selects all <input> elements with a valid value
:visited a:visited Selects all visited links

To write a selector that targets a pseudo-class, you first proceed the state with a semi-colon, followed by the name of the pseudo-class then your styles.

.myclass:hover {

}

A few common pseudo-classes are :link, :visited, :hover, :active, :first-child and :nth-child. There are more, and we’re going to see them all in a minute.

What are CSS Pseudo Elements?

The :first-child Pseudo-class

All CSS Pseudo Elements

Selector Example Example description
::after p::after Insert content after every <p> element
::before p::before Insert content before every <p> element
::first-letter p::first-letter Selects the first letter of every <p> element
::first-line p::first-line Selects the first line of every <p> element
::selection p::selection Selects the portion of an element that is selected by a user
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