diff --git a/src/librustdoc/html/static/rustdoc.css b/src/librustdoc/html/static/rustdoc.css
index 0ab130009ca0..ab5247517233 100644
--- a/src/librustdoc/html/static/rustdoc.css
+++ b/src/librustdoc/html/static/rustdoc.css
@@ -182,17 +182,24 @@ nav.sub {
 	top: 0;
 	bottom: 0;
 	overflow: auto;
-	/* Improve the sidebar display on firefox */
+}
+
+/* Improve the scrollbar display on firefox */
+* {
+	scrollbar-width: initial;
+}
+.sidebar {
 	scrollbar-width: thin;
 }
 
-/* Improve the sidebar display on webkit-based browsers */
+/* Improve the scrollbar display on webkit-based browsers */
+::-webkit-scrollbar {
+	width: 12px;
+}
 .sidebar::-webkit-scrollbar {
 	width: 8px;
 }
-
-/* Improve the sidebar display on webkit-based browsers */
-.sidebar::-webkit-scrollbar-track {
+::-webkit-scrollbar-track {
 	-webkit-box-shadow: inset 0;
 }
 
diff --git a/src/librustdoc/html/static/themes/dark.css b/src/librustdoc/html/static/themes/dark.css
index 155492e8a6a7..a2986c7b927e 100644
--- a/src/librustdoc/html/static/themes/dark.css
+++ b/src/librustdoc/html/static/themes/dark.css
@@ -30,16 +30,26 @@ pre {
 
 .sidebar {
 	background-color: #505050;
-	/* Improve the sidebar display on firefox */
+}
+
+/* Improve the scrollbar display on firefox */
+* {
+	scrollbar-color: rgb(64, 65, 67) #717171;
+}
+.sidebar {
 	scrollbar-color: rgba(32,34,37,.6) transparent;
 }
 
-/* Improve the sidebar display on webkit-based browsers */
+/* Improve the scrollbar display on webkit-based browsers */
+::-webkit-scrollbar-track {
+	background-color: #717171;
+}
+::-webkit-scrollbar-thumb {
+	background-color: rgba(32, 34, 37, .6);
+}
 .sidebar::-webkit-scrollbar-track {
 	background-color: #717171;
 }
-
-/* Improve the sidebar display on webkit-based browsers */
 .sidebar::-webkit-scrollbar-thumb {
 	background-color: rgba(32, 34, 37, .6);
 }
diff --git a/src/librustdoc/html/static/themes/light.css b/src/librustdoc/html/static/themes/light.css
index 488c34a61fb9..be173d8eb46d 100644
--- a/src/librustdoc/html/static/themes/light.css
+++ b/src/librustdoc/html/static/themes/light.css
@@ -32,16 +32,27 @@ pre {
 
 .sidebar {
 	background-color: #F1F1F1;
-	/* Improve the sidebar display on firefox */
+}
+
+/* Improve the scrollbar display on firefox */
+* {
+	scrollbar-color: rgba(36, 37, 39, 0.6) #e6e6e6;
+}
+
+.sidebar {
 	scrollbar-color: rgba(36, 37, 39, 0.6) #d9d9d9;
 }
 
-/* Improve the sidebar display on webkit-based browsers */
+/* Improve the scrollbar display on webkit-based browsers */
+::-webkit-scrollbar-track {
+	background-color: #ecebeb;
+}
+::-webkit-scrollbar-thumb {
+	background-color: rgba(36, 37, 39, 0.6);
+}
 .sidebar::-webkit-scrollbar-track {
 	background-color: #dcdcdc;
 }
-
-/* Improve the sidebar display on webkit-based browsers */
 .sidebar::-webkit-scrollbar-thumb {
 	background-color: rgba(36, 37, 39, 0.6);
 }