Examine source code of Hollow Purple :(

{
  "name": "Hollow Purple :(",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "2.png"
    },
    "colors": {
      "frame": "rgba(129, 111, 168, 1)",
      "tab_background_text": "rgba(157, 239, 245, 1)",
      "toolbar": "rgba(28, 5, 4, 0.32)",
      "bookmark_text": "rgba(157, 239, 245, 1)",
      "toolbar_field": "rgba(47, 11, 51, 1)",
      "toolbar_field_text": "rgba(157, 239, 245, 1)",
      "tab_line": "rgba(4, 2, 5, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d44eb1fb-ae49-4a17-ad7a-a27203f86089}"
    }
  }
}