I’m using Karuna and on my iPhone the drop down menu subheadings are just black blocks of colour, no text visible. I don’t know anything about coding. From searching forums I have tried deactivating plugins and reactivating, changing theme to twenty seventeen and then reloading karuna and neither worked.
Looks like your page is not hosted in WordPress.com, so it may be that you are using the self-hosted version of WordPress.org. This forum is dedicated to support for WordPress.com, so maybe you can find more help in the WordPress.org forums: https://wordpress.org/support/