enable pinch-to-zoom for android

css/reveal.css

@@ -469,8 +469,8 @@ body {
   width: 100%;
   height: 100%;
   overflow: hidden;
-  -ms-touch-action: none;
-      touch-action: none; }
+  -ms-touch-action: pinch-zoom;
+      touch-action: pinch-zoom; }
 
 .reveal .slides {
   position: absolute;

css/reveal.scss

@@ -566,7 +566,7 @@ $controlsArrowAngleActive: 36deg;
 	width: 100%;
 	height: 100%;
 	overflow: hidden;
-	touch-action: none;
+	touch-action: pinch-zoom;
 }
 
 .reveal .slides {

demo.html

@@ -12,7 +12,7 @@
 		<meta name="apple-mobile-web-app-capable" content="yes">
 		<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">
+		<meta name="viewport" content="width=device-width, initial-scale=1.0">
 
 		<link rel="stylesheet" href="css/reset.css">
 		<link rel="stylesheet" href="css/reveal.css">