Examine source code of darker-better

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "darker-better",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(20, 20, 20)",
      "toolbar_text": "rgb(128, 128, 128)",
      "frame": "rgb(20, 20, 20)",
      "tab_background_text": "rgb(108, 108, 108)",
      "toolbar_field": "rgb(32, 32, 32)",
      "toolbar_field_text": "rgb(108, 108, 108)",
      "tab_line": "rgba(254, 254, 254, 0.31)",
      "popup": "rgb(20, 20, 20)",
      "popup_text": "rgb(255, 255, 255)",
      "button_background_active": "rgb(255, 255, 255)",
      "button_background_hover": "rgb(255, 255, 255)",
      "icons_attention": "rgb(255, 255, 255)",
      "icons": "rgb(108, 108, 108)",
      "popup_border": "rgb(0, 0, 0)",
      "tab_background_separator": "rgb(32, 32, 32)",
      "tab_selected": "rgb(20, 20, 20)",
      "tab_text": "rgb(255, 255, 255)",
      "toolbar_field_border_focus": "rgb(255, 255, 255)",
      "toolbar_field_focus": "rgb(255, 255, 255)",
      "toolbar_field_highlight": "rgb(0, 0, 0)",
      "toolbar_field_text_focus": "rgb(0, 0, 0)",
      "toolbar_top_separator": "rgb(43, 43, 43)",
      "tab_loading": "rgba(254, 254, 254, 0.31)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f68bf2bd-eae1-470e-a4d6-7729a2e33729}"
    }
  }
}