javascript - 如何自定义 rPlot 标题（字体大小、字体、..）？

Question

如何更改 rPlot 标题的字体大小？

library(rCharts)
p1 <- rPlot(mpg ~ cyl, data = mtcars, type = 'point')
p1$set(title = "title",fontSize = '50px')
p1