Examine source code of The Devil in the Sky

{
  "name": "The Devil in the Sky",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "The Devil in the Sky.png"
    },
    "colors": {
      "frame": "rgba(68, 71, 79, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(70, 73, 82, 0)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(255, 255, 255, 0.53)",
      "toolbar_field_text": "rgba(3, 0, 0, 1)",
      "tab_line": "rgba(255, 0, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f74af904-c28f-4c24-a701-62d1d1a4320c}"
    }
  }
}