Examine source code of Rain World

{
  "name": "Rain World",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "0.png"
    },
    "colors": {
      "frame": "rgba(0, 0, 0, 1)",
      "tab_background_text": "rgba(145, 141, 168, 1)",
      "toolbar": "rgba(0, 0, 0, 1)",
      "bookmark_text": "rgba(145, 141, 168, 1)",
      "toolbar_field": "rgba(0, 0, 0, 1)",
      "toolbar_field_text": "rgba(145, 141, 168, 1)",
      "tab_line": "rgba(74, 78, 115, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{c0f81ac6-fd60-4065-a069-1ae742dae19c}"
    }
  }
}