How can I combine the popup cards of the component Browser mod and the style of the card mod?

Hello, I need to change the style of my popup cards created with the custom card browser mod and I would like to use card mod by adding or modifying the CSS, only I have tried them all but nothing changes, how do I do? where do I put the parameters for the style?

I have to change the background and the size of the popup card that comes out if I press the button

custo component:
https://github.com/thomasloven/hass-browser_mod
https://github.com/thomasloven/lovelace-card-mod

and my cards have this conformation:

                  - type: button
                    name: Luci
                    icon: mdi:lightbulb
                    show_state: false
                    tap_action:
                      action: call-service
                      service: browser_mod.popup
                      service_data:
                        title: Luci Camera
                        card:
                            type: vertical-stack
                            cards:
                              - type: horizontal-stack
                                cards:
                                  - type: light
                                    entity: light.lampadario           
                                  - type: light
                                    entity: light.lampada
                              - type: horizontal-stack
                                cards:
                                  - type: light
                                    entity: light.striscia_led_rgb
                              - type: entities
                                entities:
                                  - input_select.luci_timer
                                  - input_number.minuti_luci
                                  - timer.light_on
                        deviceID:
                          - this
                          - dashboard