Examine source code of tommyinnit theme !

{
  "name": "tommyinnit theme !",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "unknown.png"
    },
    "colors": {
      "frame": "rgba(128, 0, 0, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(173, 79, 79, 1)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(255, 255, 255, 1)",
      "toolbar_field_text": "rgba(117, 14, 14, 1)",
      "tab_line": "rgba(255, 255, 255, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{30f82bda-816e-4d69-a235-f685e996d541}"
    }
  }
}