Examine source code of Doom (2016) Cover

{
  "name": "Doom (2016) Cover Recreated",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "Doom Cover Recreated (2016) - Firefox Theme Header.png"
    },
    "colors": {
      "frame": "rgba(17, 5, 5, 1)",
      "tab_background_text": "rgba(204, 178, 106, 1)",
      "toolbar": "rgba(0, 0, 0, 0)",
      "bookmark_text": "rgba(204, 178, 106, 1)",
      "toolbar_field": "rgba(0, 0, 0, 0.66)",
      "toolbar_field_text": "rgba(204, 178, 106, 1)"
    }
  }
}