Examine source code of The First Mario

{
  "name": "The First Mario",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "The First Mario 2.0 (2).png"
    },
    "colors": {
      "frame": "rgba(89, 155, 255, 1)",
      "tab_background_text": "rgba(0, 0, 0, 1)",
      "toolbar": "rgba(255, 255, 255, 0.36)",
      "bookmark_text": "rgba(255, 0, 0, 1)",
      "toolbar_field": "rgba(255, 255, 255, 0.73)",
      "toolbar_field_text": "rgba(0, 0, 0, 1)",
      "tab_line": "rgba(0, 0, 0, 0.72)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{faa741fd-746c-4959-93c6-675d90949caa}"
    }
  }
}