Examine source code of Opera GX theme

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Opera GX theme",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(0, 0, 0)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(0, 0, 0)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(255, 0, 53)",
      "popup": "rgb(0, 0, 0)",
      "popup_text": "rgb(255, 0, 53)",
      "tab_loading": "rgb(255, 0, 53)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e4f42892-8d1e-41e2-aaad-797722c108de}"
    }
  }
}