Use rem instead of px for middle-dot padding

app/assets/stylesheets/framework/mixins.scss

@@ -408,7 +408,7 @@
     // scss-lint:disable DuplicateProperty
     content: '\00B7'; // middle dot fallback if browser does not support alternative content
     content: '\00B7' / ''; // tell screen readers to ignore the content https://www.w3.org/TR/css-content-3/#accessibility
-    padding: 0 6px;
+    padding: 0 0.375rem;
     font-weight: $gl-font-weight-bold;
   }