Examine source code of grey-pro

{
  "name": "grey-pro",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "grey-pro.png"
    },
    "colors": {
      "toolbar": "rgba(49, 49, 49, 1)",
      "toolbar_field": "rgba(49, 49, 49, 1)",
      "toolbar_field_text": "rgba(240, 240, 240, 1)",
      "frame": "rgba(0, 0, 0, 0)",
      "tab_background_text": "rgba(240, 240, 240, 1)",
      "bookmark_text": "rgba(240, 240, 240, 1)"
    }
  }
}