Leven: update style-child-theme-editor

leven/sass/style-child-theme-editor.scss

@@ -39,4 +39,5 @@
 
 .has-small-font-size {
 	font-family: #{map-deep-get($config-global, "font", "family", "primary")};
+	font-family: var( --font-headings, #{map-deep-get($config-global, "font", "family", "primary")} );
 }

leven/style-editor.css

@@ -992,4 +992,5 @@ table th,
  */
 .has-small-font-size {
 	font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Oxygen", "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif;
+	font-family: var(--font-headings, -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Oxygen", "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif);
 }