Examine source code of Christmas card

{
  "name": "Christmas card",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "Christmas card.jpg"
    },
    "colors": {
      "toolbar": "rgba(0, 0, 0, 0)",
      "toolbar_field": "rgba(0, 0, 0, 0)",
      "toolbar_field_text": "rgba(247, 253, 168, 1)",
      "frame": "rgba(153, 15, 15, 1)",
      "tab_background_text": "rgba(247, 253, 168, 1)",
      "bookmark_text": "rgba(247, 253, 168, 1)"
    }
  }
}