Examine source code of gruvbox-dark

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#282828",
      "tab_background_text": "#ebdbb2"
    }
  },
  "version": "2.0",
  "name": "gruvbox-dark",
  "manifest_version": 2,
  "description": "Firefox theme for the gruvbox color scheme by\n<a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/51b32595b55bba030aad1f22730eb7a787bb37c8a04d43f4a473d4b094b65ccb/https%3A//github.com/morhetz/gruvbox\">https://github.com/morhetz/gruvbox</a>"
}