Remove white border from popup

[henkdeb]

Every popup in my dashboard regularly show this white border around the popup. After some time the borders disappear and magically reappear after some time.

Can anyone help me remove it?

type: custom:mushroom-template-card
entity: sensor.neerslag_buienradar_regen_data
icon: mdi:sun
primary:     Het blijft droog
secondary: Geen regen verwacht
icon_color: white
fill_container: true
multiline_secondary: false
view_layout:
  grid-area: footer1
tap_action:
  action: fire-dom-event
  browser_mod:
    service: browser_mod.popup
    data:
      title: Regenverwachting
      dismissable: true
      style: |
        ha-dialog {
          border: none !important;
          box-shadow: none !important;
        }
      content:
        type: custom:neerslag-card
        entity: sensor.neerslag_buienradar_regen_data
        title: Regen
card_mod:
  style: >
    ha-card {
      background-color: rgba(0, 0, 0, 0) !important;
      --card-primary-font-size: 16px !important;
      --card-secondary-font-size: 14px;
    }

    ha-card:active {
      background-color: rgba(255, 255, 255, 0.15) !important;
    }

I already tried adding the following style, but that did not work. Any tips in the right direction? Thanks!

  style: |
    ha-dialog {
      border: none !important;
      box-shadow: none !important;
    }