Examine source code of Double Rainbow

{
  "name": "Double Rainbow",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "oie_2m1nYdKthIE1.jpg"
    },
    "colors": {
      "frame": "rgba(255, 255, 255, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(20, 35, 168, 0.5)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(153, 94, 196, 0.43)",
      "toolbar_field_text": "rgba(255, 255, 255, 1)",
      "tab_line": "rgba(230, 60, 145, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d755b736-a980-4130-b8b4-c71b9e159ddf}"
    }
  }
}