Align file line numbers for some Safari users

When the preference for don't allow text size smaller than is 14px
then empty lines and a slight font size difference was causing
the misalignment

Changelog: fixed

app/assets/stylesheets/framework/highlight.scss

@@ -33,6 +33,10 @@
         padding-left: 10px;
         padding-right: 10px;
         white-space: pre;
+
+        &:empty::before {
+          content: '\200b';
+        }
       }
     }
   }
@@ -46,7 +50,6 @@
     a {
       font-family: $monospace-font;
       display: block;
-      font-size: $code-font-size !important;
       white-space: nowrap;
 
       i,