Sharing some home assistant settings, if you're interested in my setup, see kit.co/altryne

Badges color change config.yaml

    badges:
      - entity: person.alex
        style:
          ha-state-label-badge:
            $:
              ha-label-badge:
                $: |
                  .label-badge .label span{
                    color: #000 !important;
                  }          
            .: |
              :host {
                {% if is_state('person.alex', 'home') %} --label-badge-red: #03A9F4; {% endif %};
                {% if not is_state('person.alex', 'home') %} --label-badge-red: #fd79a8; {% endif %}; 
                color: #fff;
              }
      - entity: person.svetik
        style:
          ha-state-label-badge:
            $:
              ha-label-badge:
                $: |
                  .label-badge .label span{
                    color: #000 !important;
                  }  
            .: |
              :host {
                --label-badge-red: #03A9F4; 
                color: #fff;
              }
      - entity: device_tracker.tesla_model_3_421628_location_tracker
        style:
          ha-state-label-badge:
            $:
              ha-label-badge:
                $: |
                  .label-badge .label span{
                    color: #000 !important;
                  }    
            .: |
              :host {
                {% if is_state('device_tracker.tesla', 'home') %} --label-badge-red: #03A9F4; {% endif %};
                {% if not is_state('device_tracker.tesla', 'home') %} --label-badge-red: #fd79a8; {% endif %}; 
                color: #fff;
              }
      - entity: alarm_control_panel.home_alarm
        style:
          ha-state-label-badge:
            $:
              ha-label-badge:
                $: |
                  .label-badge .label span{
                    color: #000 !important;
                  }  
            .: |
              :host {
                {% if is_state('alarm_control_panel.home_alarm', 'disarmed') %} 
                  --label-badge-red: #03A9F4; 
                {% endif %};  
                color: #fff;
              }

custom.js

// Monkey patch hui-view to remove overflow and show borders
customElements.whenDefined("hui-view").then( () => {
const HuiView = customElements.get("hui-view").prototype;
const oldRenderStyles = HuiView.renderStyles;
HuiView.renderStyles = function() {
  let original = oldRenderStyles();
  original.strings = [original.strings[0] + `
  <style>
    .column {
      overflow-y: visible;
    }
  </style>
  `];
  return original;
}
});

nest.yaml

# Card-Specific Modifications
ha-card-box-shadow: "10px 10px 17px -8px #A9A9A9" # Shadows on cards. Same as `shadow-elevation-2dp_-_box-shadow:
ha-card-border-radius: "10px" # Rounded corners on cards. NOTE: may not work with custom cards.
ha-card-padding: 25px;
ha-card-background: rgba(255,255,255,0.95);

# Fonts
primary-font-family: 'Open Sans,sans-serif'
paper-font-common-base_-_font-family: "var(--primary-font-family)"
paper-font-common-code_-_font-family: "var(--primary-font-family)"
paper-font-body1_-_font-family: "var(--primary-font-family)"
paper-font-subhead_-_font-family: "var(--primary-font-family)"
paper-font-headline_-_font-family: "var(--primary-font-family)"
paper-font-caption_-_font-family: "var(--primary-font-family)"
paper-font-title_-_font-family: "var(--primary-font-family)"

# Colors
# primary-text-color: # `|`'#FFFFFF' CSS color value for the color to be used.
text-primary-color: '#FFF'
primary-color: "#636B75"
secondary-text-color: "#5f6368"
text-light-color: '#BAC0C6' 
# disabled-text-color:
text-medium-color: '#8c96a5'
paper-item-icon-color: 'var(--text-light-color)'  
ha-label-badge-color: "#fff"

scenes.yaml

  - cards:
      - color: 'rgba(3, 169, 244,1.0)'
        color_type: icon
        entity: scene.good_night
        icon: 'mdi:weather-night'
        lock:
          enabled: true
        tap_action:
          action: call-service
          service: scene.turn_on
          service_data:
            entity_id: entity
        type: 'custom:button-card'
      - action: call-service
        color: 'rgba(255, 224, 130,.9)'
        color_type: icon
        entity: scene.arrive_home
        icon: 'mdi:home-map-marker'
        lock:
          enabled: true
        service: scene.turn_on
        tap_action:
          action: call-service
          service: scene.turn_on
          service_data:
            entity_id: entity
        type: 'custom:button-card'
      - action: call-service
        color: 'rgba(159, 168, 218,.9)'
        color_type: icon
        entity: scene.leave_home
        icon: 'mdi:home-export-outline'
        lock:
          enabled: true
        service: scene.turn_on
        tap_action:
          action: call-service
          service: scene.turn_on
          service_data:
            entity_id: entity
        type: 'custom:button-card'
    type: horizontal-stack

Hey,
I have the following in my configuration.yaml :

frontend:
  themes: !include_dir_named themes

And I put the nest.yaml in the themes folder