CSS Pseudo-elements

Syntax

The syntax of pseudo-elements:

selector::pseudo-element {
    property:value;
}

Notice the double colon notation - ::first-line versus :first-line

The double colon replaced the single-colon notation for pseudo-elements in CSS3. This was an attempt from W3C to distinguish between pseudo-classes and pseudo-elements.

The single-colon syntax was used for both pseudo-classes and pseudo-elements in CSS2 and CSS1.

For backward compatibility, the single-colon syntax is acceptable for CSS2 and CSS1 pseudo-elements.

The ::first-line Pseudo-element

The ::first-line pseudo-element is used to add a special style to the first line of a text.

The following example formats the first line of the text in all <p> elements:

p::first-line {
    color: #ff0000;
    font-variant: small-caps;
}

Note: The ::first-line pseudo-element can only be applied to block-level elements.

The following properties apply to the ::first-line pseudo-element:

• font properties
• color properties
• background properties
• word-spacing
• letter-spacing
• text-decoration
• vertical-align
• text-transform
• line-height
• clear

---

The ::first-letter Pseudo-element

The ::first-letter pseudo-element is used to add a special style to the first letter of a text.

The following example formats the first letter of the text in all <p> elements: 

p::first-letter {
    color: #ff0000;
    font-size: xx-large;
}

Note: The ::first-letter pseudo-element can only be applied to block-level elements.

The following properties apply to the ::first-letter pseudo- element: 

• font properties
• color properties 
• background properties
• margin properties
• padding properties
• border properties
• text-decoration
• vertical-align (only if "float" is "none")
• text-transform
• line-height
• float
• clear

---

Pseudo-elements and CSS Classes

Pseudo-elements can be combined with CSS classes: 

p.intro::first-letter {
    color: #ff0000;
    font-size:200%;
}

Multiple Pseudo-elements

Several pseudo-elements can also be combined.

In the following example, the first letter of a paragraph will be red, in an xx-large font size. The rest of the first line will be blue, and in small-caps. The rest of the paragraph will be the default font size and color:

p::first-letter {
    color: #ff0000;
    font-size: xx-large;
}

p::first-line {
    color: #0000ff;
    font-variant: small-caps;
}

CSS - The ::before Pseudo-element

The ::before pseudo-element can be used to insert some content before the content of an element.

The following example inserts an image before the content of each <h1> element:

h1::before {
    content: url(smiley.gif);
}

CSS - The ::after Pseudo-element

The ::after pseudo-element can be used to insert some content after the content of an element.

The following example inserts an image after the content of each <h1> element:

h1::after {
    content: url(smiley.gif);
}

CSS - The ::selection Pseudo-element

The ::selection pseudo-element matches the portion of an element that is selected by a user.

The following CSS properties can be applied to ::selection: color, background, cursor, and outline.

The following example makes the selected text red on a yellow background:

::selection {
    color: red; 
    background: yellow;
}