diff --git a/package/src/common/patches/revealjs-plugin-0001-chakboard-backdrop-filter.patch b/package/src/common/patches/revealjs-plugin-0001-chakboard-backdrop-filter.patch
index 0d56f5c667..e316d51096 100644
--- a/package/src/common/patches/revealjs-plugin-0001-chakboard-backdrop-filter.patch
+++ b/package/src/common/patches/revealjs-plugin-0001-chakboard-backdrop-filter.patch
@@ -1,13 +1,15 @@
 diff --git a/src/resources/formats/revealjs/plugins/chalkboard/plugin.js b/src/resources/formats/revealjs/plugins/chalkboard/plugin.js
-index 6dfb4b5a5..543ee101f 100644
+index 543ee101f..e9bd64ea3 100644
 --- a/src/resources/formats/revealjs/plugins/chalkboard/plugin.js
 +++ b/src/resources/formats/revealjs/plugins/chalkboard/plugin.js
-@@ -444,6 +444,8 @@ const initChalkboard = function ( Reveal ) {
+@@ -444,8 +444,8 @@ const initChalkboard = function ( Reveal ) {
  			container.style.visibility = 'visible';
  			container.style.pointerEvents = 'none';
  			container.style['backdrop-filter'] = 'none';
-+      // for older safari
-+      container.style["-webkit-backdrop-filter"] = "none";
+-      // for older safari
+-      container.style["-webkit-backdrop-filter"] = "none";
++			// for older safari
++			container.style["-webkit-backdrop-filter"] = "none";
  
  			var slides = document.querySelector( '.slides' );
  			var aspectRatio = Reveal.getConfig().width / Reveal.getConfig().height;
diff --git a/src/resources/formats/revealjs/plugins/chalkboard/plugin.js b/src/resources/formats/revealjs/plugins/chalkboard/plugin.js
index 543ee101fb..e9bd64ea37 100644
--- a/src/resources/formats/revealjs/plugins/chalkboard/plugin.js
+++ b/src/resources/formats/revealjs/plugins/chalkboard/plugin.js
@@ -444,8 +444,8 @@ const initChalkboard = function ( Reveal ) {
 			container.style.visibility = 'visible';
 			container.style.pointerEvents = 'none';
 			container.style['backdrop-filter'] = 'none';
-      // for older safari
-      container.style["-webkit-backdrop-filter"] = "none";
+			// for older safari
+			container.style["-webkit-backdrop-filter"] = "none";
 
 			var slides = document.querySelector( '.slides' );
 			var aspectRatio = Reveal.getConfig().width / Reveal.getConfig().height;