Node formatting overview
The format of a node refers to its appearance in terms of font face, font size, font styles such as boldfacing, italics, underlining, etc., font color and highlight color.
This is useful for visually marking one or more specially important nodes, or for giving all nodes at the same level of the tree the same style or color. For example, the upper levels of the manual have been identified by making them boldface, while the Root node uses a larger font size.
These styles may give you some ideas: