Examine source code of Dark Grey

{
  "name": "Dark Grey ",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "clear.png"
    },
    "colors": {
      "frame": "rgba(16, 17, 18, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(61, 64, 67, 1)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(37, 39, 41, 1)",
      "toolbar_field_text": "rgba(255, 255, 255, 1)"
    }
  }
}