Examine source code of FF

{
  "name": "F i r e f o x",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "rgba(232, 233, 235, 0.06)",
      "tab_background_text": "rgba(0, 0, 0, 1)",
      "bookmark_text": "rgba(5, 5, 5, 1)",
      "toolbar_field": "rgba(255, 255, 255, 0.64)",
      "toolbar_field_text": "rgba(0, 0, 0, 1)",
      "tab_line": "rgba(201, 201, 201, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{64a5b43d-e104-4a5e-9286-ed42bb9e70d7}"
    }
  }
}