Let section presentations use a different theme

exampleSite/content/example/_index.md

@@ -1,5 +1,6 @@
 +++
 title = "Example of a section presentation"
+reveal_theme = "moon"
 +++
 
 # Section Presentation

layouts/_default/baseof.html

@@ -9,7 +9,7 @@
     <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
     <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
     <link rel="stylesheet" href="{{ "css/reveal.css" | relURL }}">
-    {{ $theme := or .Site.Params.reveal_theme "black" }}
+    {{ $theme := or .Page.Params.reveal_theme .Site.Params.reveal_theme "black" }}
     <link rel="stylesheet" href="{{ printf "css/theme/%s.css" $theme | relURL }}" id="theme">
     <!-- Theme used for syntax highlighting of code -->
     <link rel="stylesheet" href="{{ "lib/css/zenburn.css" | relURL }}">