remove custom-scroll mixin

packages/rocketchat-theme/server/colors.less

@@ -34,12 +34,24 @@
 /** ----------------------------------------------------------------------------
  * Document components
  */
-html {
-	.custom-scroll(@transparent-dark, @custom-scrollbar-color, 0);
-}
 
 * {
-	.custom-scroll(@transparent-dark, @custom-scrollbar-color);
+	-webkit-overflow-scrolling: touch;
+
+	&::-webkit-scrollbar {
+		height: 8px;
+		width: 8px;
+		background: @transparent-dark;
+	}
+
+	&::-webkit-scrollbar-thumb {
+		background-color: @custom-scrollbar-color;
+		-webkit-border-radius: 50px;
+	}
+
+	&::-webkit-scrollbar-corner {
+		background-color: @transparent-dark;
+	}
 }
 
 body {

packages/rocketchat-theme/server/lesshat.less

@@ -23,25 +23,6 @@
 	transition: @process;
 }
 
-.custom-scroll(@background, @thumb, @width: 8px, @height: 8px) {
-	-webkit-overflow-scrolling: touch;
-
-	&::-webkit-scrollbar {
-		height: @height;
-		width: @width;
-		background: @background;
-	}
-
-	&::-webkit-scrollbar-thumb {
-		background-color: @thumb;
-		-webkit-border-radius: 50px;
-	}
-
-	&::-webkit-scrollbar-corner {
-		background-color: @background;
-	}
-}
-
 .gradient(@startColor: #eee, @endColor: white) {
 	background: linear-gradient(to top, @startColor, @endColor);
 }