diff --git a/data/theme/gnome-shell-high-contrast.css b/data/theme/gnome-shell-high-contrast.css
index be23adca9..66aa66b77 100644
--- a/data/theme/gnome-shell-high-contrast.css
+++ b/data/theme/gnome-shell-high-contrast.css
@@ -489,6 +489,14 @@ StScrollBar {
   color: #999999;
   font-weight: bold; }
 
+/* Extension Dialog */
+.extension-dialog .message-dialog-main-layout {
+  spacing: 24px;
+  padding: 10px; }
+
+.extension-dialog .message-dialog-title {
+  color: #b2b2a9; }
+
 /* Network Agent Dialog */
 .network-dialog-secret-table {
   spacing-rows: 15px;
diff --git a/data/theme/gnome-shell-sass b/data/theme/gnome-shell-sass
index 8e42cb424..68fff905b 160000
--- a/data/theme/gnome-shell-sass
+++ b/data/theme/gnome-shell-sass
@@ -1 +1 @@
-Subproject commit 8e42cb424f727d9bf5be4f70971042760c5925ee
+Subproject commit 68fff905b0927ff1594061d03418221c312b2f75
diff --git a/data/theme/gnome-shell.css b/data/theme/gnome-shell.css
index beafb18b5..2d041cf97 100644
--- a/data/theme/gnome-shell.css
+++ b/data/theme/gnome-shell.css
@@ -489,6 +489,14 @@ StScrollBar {
   color: #8e8e80;
   font-weight: bold; }
 
+/* Extension Dialog */
+.extension-dialog .message-dialog-main-layout {
+  spacing: 24px;
+  padding: 10px; }
+
+.extension-dialog .message-dialog-title {
+  color: #b2b2a9; }
+
 /* Network Agent Dialog */
 .network-dialog-secret-table {
   spacing-rows: 15px;
diff --git a/js/ui/extensionDownloader.js b/js/ui/extensionDownloader.js
index 0b026d2c5..6fa06279a 100644
--- a/js/ui/extensionDownloader.js
+++ b/js/ui/extensionDownloader.js
@@ -203,7 +203,7 @@ const InstallExtensionDialog = new Lang.Class({
 
         let message = _("Download and install “%s” from extensions.gnome.org?").format(info.name);
 
-        let box = new St.BoxLayout({ style_class: 'prompt-dialog-main-layout',
+        let box = new St.BoxLayout({ style_class: 'message-dialog-main-layout',
                                      vertical: false });
         this.contentLayout.add(box);
 
@@ -211,7 +211,7 @@ const InstallExtensionDialog = new Lang.Class({
         let icon = new St.Icon({ gicon: gicon });
         box.add(icon);
 
-        let label = new St.Label({ style_class: 'prompt-dialog-headline headline',
+        let label = new St.Label({ style_class: 'message-dialog-title headline',
                                    text: message });
         box.add(label);
     },