Cannot set background color

[LostInCompilation]

I'm trying to set the background color like this:

hyperline: {
            backgroundColor: '#FFFFFF',
            plugins: [
                "cpu",
                "memory",
                //"network", // Not working, crashes
                "battery",
            ]
        },

But that has no effect. I could change the background color with a custom CSS style, but that will break the hyper border plugin (the background color is now partly on top of the border, looks really distracting). Custom CSS:

css: "div.jsx-1196914242.line {\
            background-color: #293B5E;\
        }",

Any way to change the background color? I'm using Hyper 3.2.3 stable on M1 Mac.

PS: The network plugin is broken, it throws some error. But I think I read that this is already known.