r - Change facet label text and background colour

Question

How can I change the grey facet labels (A and B) into say red background with white text?

library(data.table)
A = data.table(x = 1:4, y = 1:4, z = c('A','A','B','B'))
ggplot(A) + geom_point(aes(x = x, y = y)) + facet_wrap(~z) + theme_bw()

Answer 1

You can do:

ggplot(A) +
  geom_point(aes(x = x, y = y)) +
  facet_wrap(~z) +
  theme_bw()+
  theme(strip.background =element_rect(fill="red"))+
  theme(strip.text = element_text(colour = 'white'))