progress bar width set via scale instead of width for perf

css/reveal.scss

@@ -567,10 +567,12 @@ $controlsArrowAngleActive: 36deg;
 	.reveal .progress span {
 		display: block;
 		height: 100%;
-		width: 0px;
+		width: 100%;
 
 		background-color: currentColor;
-		transition: width 800ms cubic-bezier(0.260, 0.860, 0.440, 0.985);
+		transition: transform 800ms cubic-bezier(0.260, 0.860, 0.440, 0.985);
+		transform-origin: 0 0;
+		transform: scaleX(0);
 	}
 
 /*********************************************

css/theme/template/theme.scss

@@ -299,9 +299,6 @@
 	background: rgba(0,0,0,0.2);
 	color: $linkColor;
 }
-	.reveal .progress span {
-		transition: width 800ms cubic-bezier(0.260, 0.860, 0.440, 0.985);
-	}
 
 /*********************************************
  * PRINT BACKGROUND

dist/theme/beige.css

@@ -281,9 +281,6 @@
   background: rgba(0, 0, 0, 0.2);
   color: #8b743d; }
 
-.reveal .progress span {
-  transition: width 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985); }
-
 /*********************************************
  * PRINT BACKGROUND
  *********************************************/

dist/theme/black.css

@@ -277,9 +277,6 @@ section.has-light-background, section.has-light-background h1, section.has-light
   background: rgba(0, 0, 0, 0.2);
   color: #42affa; }
 
-.reveal .progress span {
-  transition: width 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985); }
-
 /*********************************************
  * PRINT BACKGROUND
  *********************************************/

dist/theme/blood.css

@@ -280,9 +280,6 @@
   background: rgba(0, 0, 0, 0.2);
   color: #a23; }
 
-.reveal .progress span {
-  transition: width 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985); }
-
 /*********************************************
  * PRINT BACKGROUND
  *********************************************/

dist/theme/league.css

@@ -283,9 +283,6 @@
   background: rgba(0, 0, 0, 0.2);
   color: #13DAEC; }
 
-.reveal .progress span {
-  transition: width 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985); }
-
 /*********************************************
  * PRINT BACKGROUND
  *********************************************/

dist/theme/moon.css

@@ -281,9 +281,6 @@ html * {
   background: rgba(0, 0, 0, 0.2);
   color: #268bd2; }
 
-.reveal .progress span {
-  transition: width 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985); }
-
 /*********************************************
  * PRINT BACKGROUND
  *********************************************/

dist/theme/night.css

@@ -275,9 +275,6 @@
   background: rgba(0, 0, 0, 0.2);
   color: #e7ad52; }
 
-.reveal .progress span {
-  transition: width 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985); }
-
 /*********************************************
  * PRINT BACKGROUND
  *********************************************/

dist/theme/serif.css

@@ -277,9 +277,6 @@
   background: rgba(0, 0, 0, 0.2);
   color: #51483D; }
 
-.reveal .progress span {
-  transition: width 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985); }
-
 /*********************************************
  * PRINT BACKGROUND
  *********************************************/

dist/theme/simple.css

@@ -280,9 +280,6 @@ section.has-dark-background, section.has-dark-background h1, section.has-dark-ba
   background: rgba(0, 0, 0, 0.2);
   color: #00008B; }
 
-.reveal .progress span {
-  transition: width 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985); }
-
 /*********************************************
  * PRINT BACKGROUND
  *********************************************/

dist/theme/sky.css

@@ -284,9 +284,6 @@
   background: rgba(0, 0, 0, 0.2);
   color: #3b759e; }
 
-.reveal .progress span {
-  transition: width 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985); }
-
 /*********************************************
  * PRINT BACKGROUND
  *********************************************/

dist/theme/solarized.css

@@ -281,9 +281,6 @@ html * {
   background: rgba(0, 0, 0, 0.2);
   color: #268bd2; }
 
-.reveal .progress span {
-  transition: width 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985); }
-
 /*********************************************
  * PRINT BACKGROUND
  *********************************************/

dist/theme/white.css

@@ -277,9 +277,6 @@ section.has-dark-background, section.has-dark-background h1, section.has-dark-ba
   background: rgba(0, 0, 0, 0.2);
   color: #2a76dd; }
 
-.reveal .progress span {
-  transition: width 800ms cubic-bezier(0.26, 0.86, 0.44, 0.985); }
-
 /*********************************************
  * PRINT BACKGROUND
  *********************************************/

js/controllers/progress.js

@@ -55,7 +55,7 @@ export default class Progress {
 		// Update progress if enabled
 		if( this.Reveal.getConfig().progress && this.bar ) {
 
-			this.bar.style.width = this.Reveal.getProgress() * this.getMaxWidth() + 'px';
+			this.bar.style.transform = 'scaleX('+ this.Reveal.getProgress() +')';
 
 		}