::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
: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.
:time([ before <time> | after <time> | <time> to <time> ])
col.foo // td
!label /for/ input
img /usemap/ map
x /href/ y
::valuepseudo-element in CSS3-UI.