Examine source code of Seamless (for Yaru Light)

{
  "manifest_version": 2,
  "name": "Seamless (for Yaru Light)",
  "version": "1.0",
  "theme": {
    "colors": {
      "frame": [
        19,
        19,
        19
      ],
      "popup": [
        250,
        250,
        250
      ],
      "popup_text": [
        51,
        51,
        51
      ],
      "tab_background_text": [
        250,
        250,
        250
      ],
      "toolbar": [
        250,
        250,
        250
      ],
      "toolbar_field": [
        250,
        250,
        250
      ],
      "toolbar_field_text": [
        51,
        51,
        51
      ],
      "toolbar_text": [
        51,
        51,
        51
      ]
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{be54ec27-35c4-4836-8d6f-ea44a1138190}"
    }
  }
}