docs on slide backgrounds
diff --git a/README.Rmd b/README.Rmd
index 1223d62..3cd2722 100644
--- a/README.Rmd
+++ b/README.Rmd
@@ -104,6 +104,20 @@
         center: true
     ---
 
+## Slide Backgrounds
+
+Slides are contained within a limited portion of the screen by default to allow them to fit any display and scale uniformly. You can apply full page backgrounds outside of the slide area by adding a data-background attribute to your slide header element. Four different types of backgrounds are supported: color, image, video and iframe. Below are a few examples.
+
+    ## CSS color background {data-background=#ff0000}
+    
+    ## Full size image background {data-background="background.jpeg"}
+    
+    ## Video background {data-background-video="background.mp4"}
+    
+    ## Embed a web page as a background {data-background-iframe="https://example.com"}
+    
+Backgrounds transition using a fade animation by default. This can be changed to a linear sliding transition by specifying the `background-transition: slide`. Alternatively you can set data-background-transition on any slide with a background to override that specific transition.
+
 ## Reveal.js Options
 
 Reveal.js has many additional options to conigure it's behavior. You can specify any of these options using `reveal_options`, for example:
diff --git a/README.md b/README.md
index 1487b1b..7ed0e28 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,7 @@
 -   [Display Modes](#display-modes)
 -   [Incremental Bullets](#incremental-bullets)
 -   [Appearance and Style](#appearance-and-style)
+-   [Slide Backgrounds](#slide-backgrounds)
 -   [Reveal.js Options](#reveal.js-options)
 -   [Figure Options](#figure-options)
 -   [MathJax Equations](#mathjax-equations)
@@ -113,6 +114,21 @@
         center: true
     ---
 
+Slide Backgrounds
+-----------------
+
+Slides are contained within a limited portion of the screen by default to allow them to fit any display and scale uniformly. You can apply full page backgrounds outside of the slide area by adding a data-background attribute to your slide header element. Four different types of backgrounds are supported: color, image, video and iframe. Below are a few examples.
+
+    ## CSS color background {data-background=#ff0000}
+
+    ## Full size image background {data-background="background.jpeg"}
+
+    ## Video background {data-background-video="background.mp4"}
+
+    ## Embed a web page as a background {data-background-iframe="https://example.com"}
+
+Backgrounds transition using a fade animation by default. This can be changed to a linear sliding transition by specifying the `background-transition: slide`. Alternatively you can set data-background-transition on any slide with a background to override that specific transition.
+
 Reveal.js Options
 -----------------