Examine source code of skyfield

{
  "theme": {
    "images": {
      "theme_frame": "trial2.jpg"
    },
    "colors": {
      "frame": "#dbdbd8",
      "tab_background_text": "#1b214a"
    }
  },
  "version": "2.0",
  "name": "skyfield",
  "manifest_version": 2,
  "description": "An image I made playing around with some photographs I had, inspired by the sky."
}