Examine source code of Linux tux dark mode

{
  "name": "Linux tux dark mode",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "firefox theme.png"
    },
    "colors": {
      "frame": "rgba(26, 26, 26, 1)",
      "tab_background_text": "rgba(148, 162, 212, 1)",
      "toolbar": "rgba(51, 51, 51, 1)",
      "bookmark_text": "rgba(148, 162, 212, 1)",
      "toolbar_field": "rgba(74, 74, 74, 1)",
      "toolbar_field_text": "rgba(3, 3, 3, 1)",
      "tab_line": "rgba(0, 0, 0, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{65a50cb9-38f3-468d-8281-23b534da5e88}"
    }
  }
}