Examine source code of Darkmin

{
  "name": "Darkmin",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "1185681.png"
    },
    "colors": {
      "frame": "rgba(0, 0, 0, 1)",
      "tab_background_text": "rgba(189, 189, 189, 1)",
      "toolbar": "rgba(8, 8, 8, 1)",
      "bookmark_text": "rgba(189, 189, 189, 1)",
      "toolbar_field": "rgba(0, 0, 0, 1)",
      "toolbar_field_text": "rgba(189, 189, 189, 1)",
      "tab_line": "rgba(189, 189, 189, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5c5e8d77-76a8-4577-8ef0-2f7ce39b9774}"
    }
  }
}