Problems updating selected webix menu item

I’ve never used Webix before but started at a company today that wants me to help finish a project that is currently utilizing it. I’m in charge of fixing all the CSS and have done most everything, but I can’t seem to get the background-color to the color I want it to. It always chooses a green that I never put in the CSS so I’m assuming this “selected” is defined in another file but I can’t find where.

This is what my CSS code to change the background looks like:

.webix_menu .webix_list_item.webix_selected {
	background: #000
}

Hello,
You can redefine the CSS rule for webix_selected class
Just add

 .webix_menu.webix_view .webix_list_item.webix_selected {
    background-color: #000;
}

Please check the example: https://snippet.webix.com/9q95r2w9

Thank you!