Examine source code of Darker Tabs

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Dark mode",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(65, 65, 65)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(38, 38, 38)",
      "tab_background_text": "rgb(167, 167, 167)",
      "toolbar_field": "rgb(38, 38, 38)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(106, 106, 106)",
      "popup": "rgb(38, 38, 38)",
      "popup_text": "rgb(167, 167, 167)",
      "popup_highlight": "rgb(106, 106, 106)",
      "tab_selected": "rgb(65, 65, 65)",
      "tab_text": "rgb(229, 229, 229)",
      "toolbar_top_separator": "rgb(58, 58, 58)",
      "tab_loading": "rgb(106, 106, 106)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a6d07f29-6d7e-4c94-92d1-87ca1cd2e0c0}"
    }
  }
}