Merge pull request #6 from GuangchuangYu/master

do nothing if not latex or html output
diff --git a/R/kable_styling.R b/R/kable_styling.R
index ad6189a..4ede987 100644
--- a/R/kable_styling.R
+++ b/R/kable_styling.R
@@ -58,8 +58,8 @@
   kable_format <- attr(kable_input, "format")
 
   if (!kable_format %in% c("html", "latex")) {
-    stop("Please specify output format in your kable function. Currently ",
-         "generic markdown table using pandoc is not supported.")
+      message("Currently generic markdown table using pandoc is not supported.")
+      return(kable_input)
   }
   if (kable_format == "html") {
     if (is.null(full_width)) {