Examine source code of libadwaita-dark

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "libadwaita-dark",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(36, 36, 36)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(48, 48, 48)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(58, 58, 58)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(48, 48, 48)",
      "popup": "rgb(56, 56, 56)",
      "popup_text": "rgb(255, 255, 255)",
      "button_background_active": "rgb(71, 71, 71)",
      "button_background_hover": "rgb(51, 51, 51)",
      "frame_inactive": "rgb(36, 36, 36)",
      "ntp_background": "rgb(36, 36, 36)",
      "popup_border": "rgb(79, 79, 79)",
      "sidebar_border": "rgb(79, 79, 79)",
      "sidebar": "rgb(36, 36, 36)",
      "tab_loading": "rgb(36, 36, 36)",
      "tab_selected": "rgb(71, 71, 71)",
      "toolbar_bottom_separator": "rgb(79, 79, 79)",
      "toolbar_field_border_focus": "rgb(87, 114, 145)",
      "toolbar_field_border": "rgb(58, 58, 58)",
      "toolbar_field_focus": "rgb(58, 58, 58)",
      "toolbar_field_highlight_text": "rgb(166, 190, 219)",
      "toolbar_field_highlight": "rgb(56, 80, 109)",
      "toolbar_top_separator": "rgb(48, 48, 48)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9a59aebf-6cc7-4cc6-b039-4f8ba7a3429b}"
    }
  }
}