Create a WordPress menu (up to three levels) with the WP appearances built-in menu builder and convert it to a nice responsive dropdown using template tags.
Choose your colors, and whether you want a hover or click (click will be permanent on responsive break due to mobile devices‘ use of hover as a „pre-click“).
Dieses Plugin steht zum Download zur Verfügung, um in deiner selbst gehosteten WordPress-Installation verwendet zu werden.