Examine source code of Mainframe

{
  "name": "Mainframe",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "Mozilla Theme Header.png"
    },
    "colors": {
      "frame": "rgba(0, 0, 0, 1)",
      "tab_background_text": "rgba(60, 255, 0, 1)",
      "toolbar": "rgba(0, 0, 0, 1)",
      "bookmark_text": "rgba(60, 255, 0, 1)",
      "toolbar_field": "rgba(17, 87, 3, 1)",
      "toolbar_field_text": "rgba(60, 255, 0, 1)",
      "tab_line": "rgba(60, 255, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{efaead42-fa89-470d-9672-8201396a4888}"
    }
  }
}