The :active CSS pseudo-class matches when an element is being activated by the user. It allows the page to give a feedback that the activation has been detected by the browser. When interacting with a mouse, this is typically the time between the user presses the mouse button and releases it. The :active pseudo-class is also typically matched when using the keyboard tab key. It is frequently used on <a> and <button> HTML elements, but may not be limited to just those.
The :any()pseudo-class lets you quickly construct sets of similar selectors by establishing groups from which any of the included items will match. This is an alternative to having to repeat the entire selector for the one item that varies.
The :checked CSS pseudo-class selector represents any radio (<input type="radio">), checkbox (<input type="checkbox">) or option (<option> in a <select>) element that is checked or toggled to an on state. The user can change this state by clicking on the element, or selecting a different value, in which case the :checked pseudo-class no longer applies to this element, but will to the relevant one.
The :dir CSS pseudo-class matches elements based on the directionality of the text contained in it. In HTML, the direction is determined by the dir attribute. For other document types there may be other document methods for determining the language.
The :disabledCSSpseudo-class represents any disabled element. An element is disabled if it can't be activated (e.g. selected, clicked on or accept text input) or accept focus. The element also has an enabled state, in which it can be activated or accept focus.
The :emptypseudo-class represents any element that has no children at all. Only element nodes and text (including whitespace) are considered. Comments or processing instructions do not affect whether an element is considered empty or not.
The :enabled CSS pseudo-class represents any enabled element. An element is enabled if it can be activated (e.g. selected, clicked on or accept text input) or accept focus. The element also has an disabled state, in which it can't be activated or accept focus.
The :focus CSS pseudo-class is applied when an element has received focus, either from the user selecting it with the use of a keyboard or by activating with the mouse (e.g. a form input).
The :in-range CSS pseudo-class matches when an element has its value attribute inside the specified range limitations for this element. It allows the page to give a feedback that the value currently defined using the element is inside the range limits.
The :lang CSS pseudo-class matches elements based on the language the element is determined to be in. In HTML, the language is determined by a combination of the lang attribute, the <meta> element, and possibly by information from the protocol (such as HTTP headers). For other document types there may be other document methods for determining the language.
The :nth-child(an+b)CSSpseudo-class matches an element that has an+b-1 siblings before it in the document tree, for a given positive or zero value for n, and has a parent element. More simply stated, the selector matches a number of child elements whose numeric position in the series of children matches the pattern an+b.
The :nth-last-of-type CSS pseudo-class matches an element that has an+b-1 siblings with the same element name after it in the document tree, for a given positive or zero value for n, and has a parent element. See :nth-child for a more thorough description of the syntax of its argument.
The :nth-of-type(an+b) CSS pseudo-class matches an element that has an+b-1 siblings with the same element name before it in the document tree, for a given positive or zero value for n, and has a parent element. See :nth-child for a more thorough description of the syntax of its argument. This is a more flexible and useful pseudo selector if you want to ensure you're selecting the same type of tag no matter where it is inside the parent element, or what other different tags appear before it.