Pseudo-classes are used to define special states of CSS elements. They allow styling elements when a user mouses over, focuses on, visits, or activates them. Common pseudo-classes include :hover, :focus, :visited, and :active. Pseudo-classes can be used with CSS classes and selectors like :first-child to style specific elements, such as styling the first <p> element or changing the color of a link on hover. Pseudo-elements like ::before and ::after allow inserting content before or after elements.

1. CSS – Cascading Style Sheet
Pseudo-classes

2. What are Pseudo Classes
A pseudo-class is used to define a special state of an
element.
For example, it can be used to:
• Style an element when a user mouses over it
• Style visited and unvisited links differently
• Style an element when it gets focus

3. Syntax of Pseudo-Classes
selector:pseudo-class {
property:value;
}

4. Anchor Pseudo-classes
Links can be displayed in different ways:
/* unvisited link */
a:link {
color: #FF0000;
}
/* visited link */
a:visited {
color: #00FF00;
}
/* mouse over link */
a:hover {
color: #FF00FF;
}
/* selected link */
a:active {
color: #0000FF;
}

5. Pseudo-classes and CSS Classes
• Pseudo-classes can be combined with CSS classes:
• When you hover over the link in the example, it will
change color:
a.highlight:hover {
color: #ff0000;
}

6. Hover on <div>
• An example of using the :hover pseudo-class on a
<div> element:
div:hover {
background-color: #f00;
}

7. CSS - The :first-child Pseudo-
class
• The :first-child pseudo-class matches a specified
element that is the first child of another element.
li:first-child {
color: blue;
}

8. All CSS Pseudo Classes
Selector 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
:hover a:hover Selects links on mouse over
:first-child p:first-child Selects every <p> elements that is the
first child of its parent
:focus input:focus Selects the <input> element that has
focus
:last-child p:last-child Selects every <p> elements that is the
last child of its parent

9. All CSS Pseudo Elements
Selector 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