Examine source code of Thunderbird-light

{
  "name": "Thunderbird-light",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "rgba(229, 230, 232, 1)",
      "tab_background_text": "rgba(0, 0, 0, 1)",
      "bookmark_text": "rgba(0, 0, 0, 1)",
      "toolbar_field_text": "rgba(3, 3, 3, 1)",
      "tab_line": "rgba(189, 185, 185, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d4886370-7177-4613-8405-458b4b4b8f2c}"
    }
  }
}