Optional btn & input font sizes (#28068)

scss/_forms.scss

@@ -9,6 +9,7 @@
   width: 100%;
   height: $input-height;
   padding: $input-padding-y $input-padding-x;
+  font-family: $input-font-family;
   font-size: $input-font-size;
   font-weight: $input-font-weight;
   line-height: $input-line-height;