Examine source code of EasyEgg

{
  "name": "preview_large (36)",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "preview_large (36).jpg"
    },
    "colors": {
      "frame": "rgba(20, 20, 20, 1)",
      "tab_background_text": "rgba(47, 52, 212, 1)",
      "toolbar": "rgba(207, 25, 25, 1)",
      "bookmark_text": "rgba(71, 34, 34, 1)",
      "toolbar_field": "rgba(3, 2, 2, 1)",
      "toolbar_field_text": "rgba(115, 53, 53, 1)"
    }
  }
}