Examine source code of The wall is over!

{
  "name": "The wall is over!",
  "manifest_version": 2,
  "version": "66.0",
  "theme": {
    "images": {
      "theme_frame": "firefox 2.79.png"
    },
    "colors": {
      "frame": "rgba(0, 0, 0, 0)",
      "tab_background_text": "rgba(255, 196, 0, 1)",
      "toolbar": "rgba(255, 255, 255, 0)",
      "bookmark_text": "rgba(204, 0, 7, 1)",
      "toolbar_field": "rgba(0, 47, 94, 0)",
      "toolbar_field_text": "rgba(252, 219, 5, 0.9)",
      "tab_line": "rgba(250, 13, 13, 0.72)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1bf0b2f1-8820-4ff1-9913-e00fbb5967e6}"
    }
  }
}