Examine source code of Greytheme1234

{
  "name": "Greytheme1234",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "Black.png"
    },
    "colors": {
      "frame": "rgba(49, 49, 49, 1)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar": "rgba(60, 60, 60, 1)",
      "bookmark_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgba(60, 60, 60, 1)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(136, 136, 136)"
    }
  }
}