Custom CSS with knitr and markdown in R

Question

I found this great tutorial on how to modify the css formatting of a HTML report created with markdown and knitr in Rstudio. The post can be found here.

I was hoping to

Answer 1

This is the method provided by RStudio: http://www.rstudio.com/ide/docs/authoring/markdown_custom_rendering

options(rstudio.markdownToHTML = 
  function(inputFile, outputFile) {      
    require(markdown)
    markdownToHTML(inputFile, outputFile, stylesheet='custom.css')   
  }
) 

---

I've never been able to get that working properly so I do it a little differently:

I do this by creating the standard output file, then dropping the header and css code at the top in R:

tmp <- readLines("your.html") 
tmp <- tmp[-c(1:50)] # or however many lines it is before the css ends
write(tmp,"your.html")

Then I use pandoc to add my own css in a standalone file

system("pandoc -s -S your.html -c your.css -o output.html")

Answer 2

Outside of RStudio (may work in it too - I'm not sure as I don't use it much), you can use option 'markdown.HTML.stylesheet' to set a custom style sheet. It will then import everything from your .css file into the newly created html file.

Here is an example:

## Set file names
htmlName <- "test.html"
rmdName <- gsub("html","Rmd", htmlName) 
stylesheetName <- 'style.css'

## Generate rmd file from R
sink(file = rmdName, type='output') 
    cat('\n<textarea maxlength="3000" cols="70">') 
    cat("Hello World!") 
    cat('</textarea>\n') 
sink()

## Generate style sheet from R
sink(file = stylesheetName, type='output') 
    cat("textarea {color: #a10000; }\n")
sink()

## Set knitr options and knit html
require(knitr) 
options(markdown.HTML.stylesheet = stylesheetName)
knit2html(rmdName, output = htmlName)