diff --git a/R/revealjs_presentation.R b/R/revealjs_presentation.R
index 950b8b8..f641284 100644
--- a/R/revealjs_presentation.R
+++ b/R/revealjs_presentation.R
@@ -33,6 +33,12 @@
 #' ```
 #' to create notes only viewable in presentation mode.
 #' 
+#' On mobile browsers (touch devices), a button next to the fullscreen
+#' toggle overlays the current slide with its speaker notes (plus the slide
+#' title and, if present, the planned time from a timing comment), which is
+#' useful for practicing a talk on a phone or tablet. It follows along as
+#' you change slides and only appears if the deck contains notes at all.
+#' 
 #' ## Slide timing
 #' 
 #' Speaker time can be planned per slide and per speaker by adding a comment