This pseudo-class is called target pseudo-class and represents an element which matches against fragment identifier of the URI. For example an URI is pointing to anchor named
partHelp like here:
https://example.com/test.html#partHelp the element with the ID
partHelp will be selected by this selector.
/* declarations */
outline: red dotted;
The element with the fragment identifier of the URI will have a red dotted outline border around itself.Try example in CodePen