Examine source code of Better Start Page

{
  "manifest_version": 2,
  "name": "Better Start Page",
  "description": "Minimalistic beautiful bookmarks in the new tab and homepage. Add or edit all of your bookmarks in Bookmark Manager.",
  "version": "1.5",
  "permissions": [
    "bookmarks"
  ],
  "chrome_url_overrides": {
    "newtab": "newtab.html"
  },
  "chrome_settings_overrides": {
    "homepage": "newtab.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5e9cb1df-2d42-41ef-bf55-22a7173e3790}",
      "strict_min_version": "58.0"
    }
  }
}