Examine source code of Grey w dark

{
  "name": "Grey w dark",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "222222222.png"
    },
    "colors": {
      "frame": "rgba(99, 99, 99, 1)",
      "tab_background_text": "rgba(0, 0, 0, 1)",
      "toolbar": "rgba(0, 0, 0, 0.8)",
      "bookmark_text": "rgba(0, 0, 0, 1)",
      "toolbar_field": "rgba(99, 99, 99, 1)",
      "toolbar_field_text": "rgba(0, 0, 0, 1)",
      "tab_line": "rgba(0, 0, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4183b5b4-586a-4221-b70e-5a2e257ba88d}"
    }
  }
}