Examine source code of Earl Grey

{
  "name": "Earl Grey",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "rainbow-transparent-pixel.png"
    },
    "colors": {
      "frame": "rgba(252, 251, 249, 1)",
      "tab_background_text": "rgba(96, 90, 82, 1)",
      "toolbar": "rgba(247, 243, 238, 1)",
      "bookmark_text": "rgba(85, 105, 149, 1)",
      "toolbar_field": "rgba(247, 243, 238, 1)",
      "toolbar_field_text": "rgba(85, 105, 149, 1)",
      "tab_line": "rgba(85, 105, 149, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{713d2d68-d0f0-45ce-8ce5-a20ba57ffd51}"
    }
  }
}