1. A method for content driven selection of a rendering engine, the method comprising: retrieving from a content source from over a computer communications network content for display in a content browser executing in memory by a processor of a host computer; parsing the content and detecting, in response to the parsing, multiple different content rendering directives embedded in the retrieved content; comparing the parsed and detected directives to a table of known directives and corresponding target rendering engines, each target rendering engine comprising a layout engine, the table indicating incompatibilities between different content rendering directives and corresponding ones of the different target rendering engines; determining from the comparison in the table for each one of the parsed and detected directives a corresponding one of the target rendering engines and mapping each one of the parsed and detected directives to the corresponding one of the target rendering engines; selecting one of the mapped target rendering engines as a target rendering engine for rendering the content despite the table indicating an incompatibility on condition that at least one counterbalancing directive is present in the content to negate an impact of the incompatibility indicated in the table; and, passing the content to the selected one of the mapped target rendering engines.