A styling layer for 'ggplot2'. A 'style_spec()' object holds colors, scales, geom aesthetics, legends, axes, and theme; 'style_plot()' applies it to a finished plot, giving a set of packages one consistent way to let users style the plots they produce. 'reveal()' maps a column that is in a plot's data but not shown onto a graphical channel or a facet, so a covariate behind an unexplained pattern can be added to the plot it came from.