Examine source code of Startpage Dark

{
  "name": "Startpage Dark",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "startpage-night.png"
    },
    "colors": {
      "frame": "rgba(12, 13, 15, 1)",
      "tab_background_text": "rgba(191, 202, 255, 1)",
      "toolbar": "rgba(41, 45, 57, 1)",
      "bookmark_text": "rgba(191, 202, 255, 1)",
      "toolbar_field": "rgba(12, 13, 15, 1)",
      "toolbar_field_text": "rgba(255, 255, 255, 1)",
      "tab_line": "rgba(191, 202, 255, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{2d825ee9-2b22-4049-ad49-474e13c8eb16}"
    }
  }
}