Examine source code of alone...

{
  "theme": {
    "images": {
      "theme_frame": "adoveinamarsh.png"
    },
    "colors": {
      "frame": "#ffffff",
      "tab_background_text": "#010c33"
    }
  },
  "version": "2.0",
  "name": "alone...",
  "manifest_version": 2,
  "description": "dove-colombe-marsh-marais-bird-oiseau"
}