Examine source code of Nostalgic Bird

{
  "name": "Nostalgic Bird",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "1920px-Mozilla_Phoenix_logo_vector.svg.png"
    },
    "colors": {
      "frame": "rgba(227, 229, 232, 0)",
      "tab_background_text": "rgba(153, 153, 153, 1)",
      "toolbar": "rgba(209, 109, 109, 0.45)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(255, 255, 255, 0.55)",
      "toolbar_field_text": "rgba(143, 52, 52, 1)"
    }
  }
}