Examine source code of Adwaita Black Theme

{
  "manifest_version": 2,
  "version": "1.1",
  "name": "Adwaita Black Theme",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(53, 53, 53)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(45, 45, 45)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(45, 45, 45)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(21, 83, 158)",
      "popup": "rgb(45, 45, 45)",
      "popup_text": "rgb(255, 255, 255)",
      "ntp_background": "rgb(45, 45, 45)",
      "popup_highlight": "rgb(21, 83, 158)",
      "toolbar_field_border_focus": "rgb(21, 83, 158)",
      "toolbar_field_border": "rgb(27, 27, 27)",
      "tab_loading": "rgb(21, 83, 158)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e15af950-748e-43a8-af92-f29f621509c2}"
    }
  }
}