Examine source code of Medium dark borealis

{
  "name": "Medium dark",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "Frederic_Edwin_Church_-_Aurora_Borealis_-_Google_Art_Project.jpg"
    },
    "colors": {
      "frame": "rgba(77, 77, 77, 0.7)",
      "tab_background_text": "rgba(180, 180, 180, 1)",
      "toolbar": "rgba(87, 87, 87, 0.7)",
      "bookmark_text": "rgba(222, 222, 222, 1)",
      "toolbar_field": "rgba(150, 150, 150, 0.7)",
      "toolbar_field_text": "rgba(255, 255, 255, 0.7)",
      "tab_line": "rgba(100, 100, 100, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a17a87a6-27f6-4c1c-8876-f196ff01b1e6}"
    }
  }
}