Do you want to know how the CSS WG works? Fantasai has written about:csswg, An Inside View of the CSS Working Group at W3C.
Note that the ‘direction’ property is often set by rules in the UA style sheet based on mark-up in the document, as recommended in CSS 2.1 [CSS21] section 9.10 (“Text direction: the ‘direction’ and ‘unicode-bidi’ properties”).
When formatting content in the page model, some content may end up outside the current page box. For example, an element whose ‘white-space’ property has the value ‘pre’ may generate a box that is wider than the page box. As another example, when boxes are positioned absolutely or relatively, they may end up in “inconvenient” locations. For example, images may be placed on the edge of the page box or 100,000 meters below the page box.