diff --git a/R/revealjs_presentation.R b/R/revealjs_presentation.R
index 9a41437..82691b2 100644
--- a/R/revealjs_presentation.R
+++ b/R/revealjs_presentation.R
@@ -86,6 +86,7 @@
                                   highlight = "default",
                                   mathjax = "default",
                                   template = "default",
+                                  css = NULL,
                                   includes = NULL,
                                   keep_md = FALSE,
                                   lib_dir = NULL,
@@ -138,6 +139,10 @@
   # content includes
   args <- c(args, includes_to_pandoc_args(includes))
   
+  # additional css
+  for (css_file in css)
+    args <- c(args, "--css", pandoc_path_arg(css_file))
+  
   # pre-processor for arguments that may depend on the name of the
   # the input file (e.g. ones that need to copy supporting files)
   pre_processor <- function(metadata, input_file, runtime, knit_meta, files_dir,
diff --git a/man/revealjs_presentation.Rd b/man/revealjs_presentation.Rd
index b9544fe..bd60117 100644
--- a/man/revealjs_presentation.Rd
+++ b/man/revealjs_presentation.Rd
@@ -1,4 +1,4 @@
-% Generated by roxygen2 (4.1.0): do not edit by hand
+% Generated by roxygen2 (4.1.1): do not edit by hand
 % Please edit documentation in R/revealjs_presentation.R
 \name{revealjs_presentation}
 \alias{revealjs_presentation}
@@ -9,8 +9,8 @@
   smart = TRUE, self_contained = TRUE, theme = "default",
   transition = "default", background_transition = "default",
   highlight = "default", mathjax = "default", template = "default",
-  includes = NULL, keep_md = FALSE, lib_dir = NULL, pandoc_args = NULL,
-  ...)
+  css = NULL, includes = NULL, keep_md = FALSE, lib_dir = NULL,
+  pandoc_args = NULL, ...)
 }
 \arguments{
 \item{incremental}{\code{TRUE} to render slide bullets incrementally. Note
@@ -68,6 +68,8 @@
   then some features of \code{revealjs_presentation} won't be available
   (see the Templates section below for more details).}
 
+\item{css}{One or more css files to include}
+
 \item{includes}{Named list of additional content to include within the
 document (typically created using the \code{\link{includes}} function).}