In Rstudio rmarkdown, how to add new html themes from Bootswatch?

[nietzschetmh]

I think i found the solution

1. Download bootstrap.css file from https://bootswatch.com/
2. Put the bootstrap.css file in the same folder with your rmd file.
3. Change rmd code to this

title: "test"
author: "test" 
output: 
    html_document:
        css: bootstrap.css