Examine source code of Death Valley Fox

{
  "name": "Death Valley Fox",
  "manifest_version": 2,
  "version": "4.0",
  "theme": {
    "images": {
      "theme_frame": "skull-fox.png"
    },
    "colors": {
      "frame": "rgba(229, 230, 232, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(156, 138, 0, 0.16)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(107, 105, 0, 0.46)",
      "toolbar_field_text": "rgba(255, 252, 252, 1)",
      "tab_line": "rgba(209, 232, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4ef50281-a108-4960-b944-24922cd2a8ca}"
    }
  }
}