fix centering of edge-aligned controls

css/reveal.css

@@ -400,16 +400,20 @@ body {
     right: auto; }
   .reveal .controls[data-controls-layout="edges"] .navigate-left {
     top: 50%;
-    left: 8px; }
+    left: 8px;
+    margin-top: -1.8em; }
   .reveal .controls[data-controls-layout="edges"] .navigate-right {
     top: 50%;
-    right: 8px; }
+    right: 8px;
+    margin-top: -1.8em; }
   .reveal .controls[data-controls-layout="edges"] .navigate-up {
     top: 8px;
-    left: 50%; }
+    left: 50%;
+    margin-left: -1.8em; }
   .reveal .controls[data-controls-layout="edges"] .navigate-down {
     bottom: 8px;
-    left: 50%; } }
+    left: 50%;
+    margin-left: -1.8em; } }
 
 /*********************************************
  * PROGRESS BAR

css/reveal.scss

@@ -477,21 +477,25 @@ $controlsArrowAngleActive: 36deg;
 		.navigate-left {
 			top: 50%;
 			left: $spacing;
+			margin-top: -$controlArrowSize/2;
 		}
 
 		.navigate-right {
 			top: 50%;
 			right: $spacing;
+			margin-top: -$controlArrowSize/2;
 		}
 
 		.navigate-up {
 			top: $spacing;
 			left: 50%;
+			margin-left: -$controlArrowSize/2;
 		}
 
 		.navigate-down {
 			bottom: $spacing;
 			left: 50%;
+			margin-left: -$controlArrowSize/2;
 		}
 	}
 

js/reveal.js

@@ -4965,7 +4965,7 @@
 		this.context.beginPath();
 		this.context.arc( x, y, radius, 0, Math.PI * 2, false );
 		this.context.lineWidth = this.thickness;
-		this.context.strokeStyle = '#666';
+		this.context.strokeStyle = 'rgba( 255, 255, 255, 0.2 )';
 		this.context.stroke();
 
 		if( this.playing ) {