fix(div): update class name to remove weird space afterwards (#763)

Signed-off-by: Aaron <29749331+aarnphm@users.noreply.github.com>

quartz/util/lang.ts

@@ -9,3 +9,13 @@ export function pluralize(count: number, s: string): string {
 export function capitalize(s: string): string {
   return s.substring(0, 1).toUpperCase() + s.substring(1)
 }
+
+export function classNames(
+  displayClass?: "mobile-only" | "desktop-only",
+  ...classes: string[]
+): string {
+  if (displayClass) {
+    classes.push(displayClass)
+  }
+  return classes.join(" ")
+}