Examine source code of Thunder!!

{
  "name": "Thunder!!",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "image.jpg"
    },
    "colors": {
      "frame": "rgba(242, 238, 237, 1)",
      "tab_background_text": "rgba(15, 13, 13, 1)",
      "toolbar": "rgba(66, 88, 150, 1)",
      "bookmark_text": "rgba(237, 244, 250, 0.95)",
      "toolbar_field": "rgba(242, 234, 233, 1)",
      "toolbar_field_text": "rgba(0, 0, 0, 1)"
    }
  }
}