Examine source code of darker that black

{
  "theme": {
    "images": {
      "theme_frame": "Untitled-1.jpg"
    },
    "colors": {
      "frame": "#ff0a0a",
      "tab_background_text": "#f0e2e2"
    }
  },
  "version": "2.0",
  "name": "darker that black",
  "manifest_version": 2
}