CSS DSL for R

css.R

library(shiny)

css <- local({
  cssRules <- function(rules) {
    paste(
      '  ',
      gsub('.', '-', names(rules), fixed = TRUE),
      ': ',
      rules,
      ';',
      sep = '')
  }

  function(...) {
    selectors <- list(...)
    if (length(selectors) == 0)
      return(NULL)
    
    lines <- unlist(lapply(1:length(selectors), function(i) {
      name <- names(selectors)[[i]]
      value <- selectors[[i]]
      c(paste(name, ' {', sep=''),
        cssRules(value),
        '}')
    }))
    
    do.call(tags$style, c(list(type='text/css'), lines))
  }  
})

examples

# tests

tags$style(type="text/css",
  ".search {",
  "  font-family: Source Sans Pro;",
  "  font-size: 12px;",
  "}",
  "#foo.bar span a {",
  "  margin-top: 8px;",
  "  margin-bottom: 0;",
  "}"
)

css(
  .search = c(
    font.family = "Source Sans Pro",
    font.size = "12px"
  ),
  "#foo.bar span a" = c(
    margin.top = "8px",
    margin.bottom = 0
  )
)