::quote-start and ::quote-end, to match characters with the Quotation_Mark property that are direct children of the element and that are immediately inside the start and end (respectively) of the element, ignoring White_Space characters. (This would help a lot with <q> in HTML5.):placeholder - matches form elements displaying placeholder text. This allows web developers and theme designers to customize the appearance of placeholder text, which is a light grey color by default. This may not work well if you've changed the background color of your form fields to be a similar color, for example, so you can use this pseudo-class to change the placeholder text color.::window pseudo-element::first-words(n), ::first-lines(n), ::nth-line(an+b), ::last-line etc.:link etc.:time([ before <time> | after <time> | <time> to <time> ])col.foo // td!label /for/ inputimg /usemap/ mapx /href/ y:matches() and $::value pseudo-element in CSS3-UI.