ABCpdf includes two HTML rendering engines.
The MSHTML one is based around Trident and will produce output broadly similar to the version of IE installed on your system.
The Gecko one is based around Firefox and as of June 2013 will produce output broadly similar to that you see in Firefox 21.
You can switch between the two engines using the Doc.HtmlOptions.Engine property.
Both engines support the page-break CSS styles. You can use the following:
<div style="page-break-before:always">some text</div>
<div style="page-break-after:always">some text</div>
<div style="page-break-inside:avoid">some text</div>
Note that the page-break-inside is an addition to the base MSHTML behavior.
The two engines treat these constructs slightly differently. In general MSHTML is more forgiving and intuitive. Howwever the element to which the style is applied must be visible for it to work.
As such, if the styles don't produce breaks in the places you would expect, the easiest way to debug them is to apply a border style to the element so you can see where the break should occur. This normally makes the cause of the problem obvious.
The page break styles in the Gecko engine are not always applied as intuitively as they are in MSHTML. The root of this is the CSS specification that which says that break styles must be appliable to block-level elements within the "normal flow of the root element". It allows for these styles to be applied to other elements but does not mandate it.
The upshot of this, within the Gecko engine, is that page break styles cannot be applied within tables, to elements such as table rows. If you are unsure about whether something is likely to work just try Print Preview from within Firefox 21.0 as a simple sanity check.
page-break: before;
upon selected elements. – Razee