<h/> — Depth-based headings because big headings are ugly

HTML uses numbered headings, prodoc, on the other hand, uses nested divs with a single, context-sensitive <h/> element

The following XPath scales headings based on the maximum depth of the document. 1.272 is the square root of the golden ratio. A recent document needed a gentler scaling factor. The cube root of the golden ratio (1.174) was used, instead.

Figure 19. CSS to scale headings based on document depth

h {
font-size : oxy_xpath("concat(
            math:pow(1.272,((max(//h/count(ancestor::*[@display='div'])) - count(ancestor::*[@display='div']) + 1 ))),
            'em')", evaluate,dynamic-once) ;