Some very handy classes and selectors to know.
a:link Selects all unvisited links a:visited Selects all visited links a:hover Selects links on mouse hover a:active Selects the active link element p:after Insert content inside </p> element p:before Insert content inside <p> element p::after Insert content after </p> element p::before Insert content before <p> element input:checked Selects every checked <input> element input:disabled Selects every disabled <input> element input:enabled Selects every enabled <input> element input:focus Selects the <input> element which has focus input:in-range Selects <input> elements with a value within a specified range input:invalid Selects all <input> elements with an invalid value input:optional Selects <input> elements with no ‘required’ attribute input:out-of-range Selects <input> elements with a value outside a specified range input:read-only Selects <input> elements with the ‘readonly’ attribute specified input:read-write Selects <input> elements with the ‘readonly’ attribute not specified input:required Selects <input> elements with the ‘required’ attribute specified p:empty Selects every <p> element with no children p:first-child Selects every <p> element that is the first child of its parent p::first-letter Selects the first letter of every <p> element p::first-line Selects the first line of every <p> element p:first-of-type Selects every <p> element that is the first <p> element of its parent p:lang(language) Selects all <p> elements with a lang attribute equal to ‘language’ p:last-child Selects every <p> element which is the last child of its parent p:last-of-type Selects every <p> element which is the last <p> element of its parent :not(p) Selects every element that is not a <p> p:nth-child(even) Selects every second <p> element p:nth-child(odd) Selects odd <p> elements p:nth-child(2) Selects every <p> element that is the second child of its parent p:nth-last-child(2) Selects every <p> element that is the second child of its parent, counting from the last child p:nth-last-of-type(2) Selects every <p> element that is the second <p> element of its parent, counting from the last child p:nth-of-type(2) Selects every <p> element that is the second <p> element of its parent p:only-of-type Selects every <p> element that is the only <p> element of its parent p:only-child Selects every <p> element that is the only child of its parent :root Selects the documents root element ::selection Selects the portion of an element that is selected by a user #id:target Selects the current active #id element input:valid Selects all <input> elements with a valid value
