Minor Sass consistency changes. (#24677)

* use `background-color` instead of the shorthand
* use `outline: 0` consistently
* fix transform order
* remove quotes from `SFMono-Regular`

scss/_close.scss

@@ -22,7 +22,7 @@
 // stylelint-disable property-no-vendor-prefix, selector-no-qualifying-type
 button.close {
   padding: 0;
-  background: transparent;
+  background-color: transparent;
   border: 0;
   -webkit-appearance: none;
 }