Examine source code of MarbleGreen

{
  "theme": {
    "images": {
      "theme_frame": "MarbleGreenHeader.jpg"
    },
    "colors": {
      "frame": "#a1f7ab",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "MarbleGreen",
  "manifest_version": 2,
  "description": "Suggestions or requests? <a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/9ab55f1bd22d9a4419edba324108fef6b7dd57cde20b1cc26275f5919b388c8f/http%3A//eprintpro.net\">http://eprintpro.net</a>"
}