Examine source code of Adwaita - Dark - Theme

{
  "manifest_version": 2,
  "version": "4.0",
  "name": "Adwaita Dark",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(53, 53, 53)",
      "toolbar_text": "rgb(238, 238, 236)",
      "frame": "rgb(40, 40, 40)",
      "tab_background_text": "rgb(238, 238, 236)",
      "toolbar_field": "rgb(40, 40, 40)",
      "toolbar_field_text": "rgb(238, 238, 236)",
      "tab_line": "rgb(53, 53, 53)",
      "popup": "rgb(53, 53, 53)",
      "popup_text": "rgb(238, 238, 236)",
      "button_background_active": "rgb(53, 53, 53)",
      "button_background_hover": "rgb(53, 53, 53)",
      "icons_attention": "rgb(239, 41, 41)",
      "icons": "rgb(238, 238, 236)",
      "ntp_background": "rgb(53, 53, 53)",
      "ntp_text": "rgb(238, 238, 236)",
      "popup_border": "rgb(27, 27, 27)",
      "popup_highlight_text": "rgb(238, 238, 236)",
      "popup_highlight": "rgb(21, 83, 158)",
      "sidebar_border": "rgb(27, 27, 27)",
      "sidebar_highlight_text": "rgb(238, 238, 236)",
      "sidebar_highlight": "rgb(21, 83, 158)",
      "sidebar_text": "rgb(238, 238, 236)",
      "sidebar": "rgb(53, 53, 53)",
      "tab_background_separator": "rgb(238, 238, 236)",
      "tab_loading": "rgb(238, 238, 236)",
      "tab_selected": "rgb(53, 53, 53)",
      "toolbar_bottom_separator": "rgb(27, 27, 27)",
      "toolbar_field_border_focus": "rgb(27, 27, 27)",
      "toolbar_field_border": "rgb(27, 27, 27)",
      "toolbar_field_focus": "rgb(46, 46, 46)",
      "toolbar_field_highlight_text": "rgb(238, 238, 236)",
      "toolbar_field_highlight": "rgb(21, 83, 158)",
      "toolbar_field_separator": "rgb(27, 27, 27)",
      "toolbar_top_separator": "rgb(27, 27, 27)",
      "toolbar_vertical_separator": "rgb(27, 27, 27)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d4bad9d3-bf7b-4cfc-98b4-f2bb6b7adc25}"
    }
  }
}