fixes #18330

scss/_reboot.scss

@@ -77,6 +77,15 @@ body {
   background-color: $body-bg;
 }
 
+// Suppress the focus outline on elements that cannot be accessed via keyboard.
+// This prevents an unwanted focus outline from appearing around elements that
+// might still respond to pointer events.
+//
+// Credit: https://github.com/suitcss/base
+[tabindex="-1"]:focus {
+  outline: none !important;
+}
+
 
 //
 // Typography