Examine source code of Graphite Grace

{
  "manifest_version": 2,
  "name": "Graphite Grace by Slash Mark",
  "short_name": "Graphite Grace",
  "version": "1.0",
  "description": "A refined graphite-grey Firefox UI theme by Slash Mark. Elegant, professional, and image-free.",
  "author": "Slash Mark",
  "applications": {
    "gecko": {
      "id": "graphite-grace@slashmark.in"
    }
  },
  "homepage_url": "https://slashmark.in",
  "theme": {
    "colors": {
      "frame": "#1c1c1c",
      "tab_background_text": "#dcdcdc",
      "toolbar": "#262626",
      "toolbar_text": "#ffffff",
      "toolbar_field": "#303030",
      "toolbar_field_text": "#ffffff",
      "popup": "#303030",
      "popup_text": "#ffffff",
      "popup_border": "#4a4a4a",
      "ntp_background": "#1c1c1c",
      "ntp_text": "#dcdcdc"
    }
  }
}