Examine source code of backgrad

{
  "name": "backgrad",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "backgrad.png"
    },
    "colors": {
      "frame": "rgba(17, 80, 120, 1)",
      "tab_background_text": "rgba(28, 28, 28, 1)",
      "toolbar_field": "rgba(18, 51, 74, 1)",
      "tab_line": "rgba(133, 133, 133, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{6bb42c74-3b6d-4bff-812f-5b940107f653}"
    }
  }
}