This theme is designed to be a foundation from which to build new
themes, and not meant to be used directly. theme_foundation()
is a complete theme with only minimal number of elements defined.
It is easier to create new themes by extending this one rather
than theme_gray() or theme_bw(),
because those themes define elements deep in the hierarchy.
tema_base(base_size = 12, base_family = "")base font size, given in pts.
base font family
This theme takes theme_gray() and sets all
colour and fill values to NULL, except for the top-level
elements (line, rect, and title), which have
colour = "black", and fill = "white". This leaves the spacing
and-non colour defaults of the default ggplot2 themes in place.