CSS Problem - Dark Theme

I am using app-hub with Linux Mint xfcde in dark theme mode.

The icons to reduce or exit are black and invisible, please create a dark mode

[Joomzie]

This app is made for COSMIC, not XFCE. It's not a GTK app, and the "dark mode" comes from COSMIC's own theming engine. It works by applying a custom color scheme to adw-gtk3-dark, and the window control buttons follow an accent color.