These Pseudo-classes only apply with the @Page
rule used to define styles for Page Boxes. All printed pages will automatically
be classified as either a :left or :right Pseudo-class. The first printed page
of a document is addressable via the :first Pseudo-class.
Example
Ext/Doc: @page:left
{ margin: 4cm }
Notes
:left/:right has higher precedence than no Pseudo-class at all.
@Page At-Rule style rules applied using :left or :right Pseudo-classes
should override similar @Page style rules that do not have these
Pseudo-classes applied.
:first has higher precedence than :left or :right @Page At-Rule style
rules applied using the :first Pseudo-class should override similar
@Page style rules applied using :left or :right.