You can simply change layout mode to Dark by doing the below changes in the file views/partials/main.ejs.

Simply replace the attribute data-layout-mode="dark" data-sidebar="dark" data-topbar="dark" data-bs-theme="dark" data-sidebar-size="lg" data-preloader="disable" to the html tag. It will update the layout mode to Dark mode. No need to change any css or js files.