What does this operator (::) in CSS mean? [duplicate] - html

Question

This question already has answers here:
What does the double colon (::) mean in CSS?
(3 answers)
Closed 8 years ago.
I have seen CSS like Custom Scrollbars in WebKit
body::-webkit-scrollbar {
width: 10px;
height: 13px;
background-color: white;
color: #EBEBEB;
border:none;
}
This specifies CSS for WebKit browsers. But what does this operator (::) mean in CSS?
Where can I find other such operators in CSS?

Answer 1

It indicates that what follows is a "pseudo-element". From the CSS Selectors level 3 spec:
A pseudo-element is made of two colons (::) followed by the name of
the pseudo-element.
And a pseudo-element creates an "abstraction about the document tree":
Pseudo-elements create abstractions about the document tree beyond
those specified by the document language. For instance, document
languages do not offer mechanisms to access the first letter or first
line of an element's content. Pseudo-elements allow authors to refer
to this otherwise inaccessible information. Pseudo-elements may also
provide authors a way to refer to content that does not exist in the
source document (e.g., the ::before and ::after pseudo-elements give
access to generated content).
For example, the ::webkit-scrollbar pseudo-element provides a mechanism to refer to the webkit scrollbar, which would be otherwise inaccessible. Another example: the ::first-letter pseudo-element provides a way to refer to the first letter of an element (if it is not preceded by any other content).

Answer 2

In css3 we use double colon(::) for pseudo-element & single colon(:) for pseudo-class
The single colon syntax (e.g. “:before” or “:first-child”) is the
syntax used for both pseudo-classes and pseudo-selectors in all
versions of CSS prior to CSS3. With the introduction of CSS3, in order
to make a differentiation between pseudo-classes and pseudo-elements
(yes, they’re different), in CSS3 all pseudo-elements must use the
double-colon syntax, and all pseudo-classes must use the single-colon
syntax.
Read this article http://www.impressivewebs.com/before-after-css3/

Answer 3

It is used to define a pseudo-element. As an example from the documentation:
p::first-line { text-transform: uppercase }
This modifies the first line of p elements. There's no real DOM element that is selected, that is why it is a pseudo-element.
In your case, it modifies scrollbars in WebKit within the body element:
body::-webkit-scrollbar
There is no scrollbar element within your document but this still allows you to style scrollbars within your HTML page.

Answer 4

this operator is new add in CSS3.it's meaning Pseudo element.

Answer 5

Thought I'd add this since people are having difficulty understanding what it actually means:
Basically it's a way to get a document to format in a way that wouldn't be possible using the markup that is present. A good example exists in the W3 spec:
Here is the example for a ::first-letter pseudo element
The original HTML fragment
<div>
<p>The first text.
The fictional markup after the pseudo element is applied
<div>
<p><div::first-letter><p::first-letter>T</...></...>he first text.
As you can see - the original HTML specified a div and a p, but there is no way to format the first letter using standard CSS, so the pseudo elements were added, enabling the first letter to be modified
Psuedo elements allow you to do stuff like that..

Answer 6

Google is your friend here.
Pseudo-elements
Pseudo-elements create abstractions about the document tree beyond those specified by the document language. For instance, document languages do not offer mechanisms to access the first letter or first line of an element's content. Pseudo-elements allow authors to refer to this otherwise inaccessible information. Pseudo-elements may also provide authors a way to refer to content that does not exist in the source document (e.g., the ::before and ::after pseudo-elements give access to generated content).
A pseudo-element is made of two colons (::) followed by the name of the pseudo-element.
This :: notation is introduced by the current document in order to establish a discrimination between pseudo-classes and pseudo-elements. For compatibility with existing style sheets, user agents must also accept the previous one-colon notation for pseudo-elements introduced in CSS levels 1 and 2 (namely, :first-line, :first-letter, :before and :after). This compatibility is not allowed for the new pseudo-elements introduced in this specification.
Found at http://www.w3.org/TR/css3-selectors