Page layout for blank pages
The properties such as blank, not-blank, odd-or-even, and page-position define criteria for applying specific styling rules. For 'blank-or-not-blank', it determines if the webpage contains actual content or if it's a blank page rendered because of a style instruction like break-before: odd-page or force-page-count: end-on-even in CSS. A page that inherits content from an HTML element, even if the content is something like a <div></div> that doesn't display anything, is considered non-blank. The values for 'blank-or-not-blank' are: 'blank' (page rendered just to fulfill style requirements); 'not-blank' (page has content); and 'any' (any page). By default, the value is 'any', which always holds true, so 'blank-or-not-blank' is typically left out unless defining styles specifically for blank pages.
This document has only enough text for one page, but -ah-force-page-count: 3; is specified to force this page sequence to generate three pages. Two blank pages were generated to satisfy the constraint. @-rules for this document specify separate page layout for blank and non-blank pages. The page layout for blank pages specifies a blue background.
The page rule @page :blank allows for style specification in each blank page instance.