Examine source code of Yesterdays Gone

{
  "name": "Yesterdays Gone",
  "manifest_version": 2,
  "version": "4.0",
  "theme": {
    "images": {
      "theme_frame": "YesterdaysGoneH.jpg"
    },
    "colors": {
      "frame": "rgba(173, 173, 173, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(135, 132, 132, 0)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(150, 150, 150, 0.11)",
      "toolbar_field_text": "rgba(255, 255, 255, 1)",
      "tab_line": "rgba(255, 255, 255, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{adab3717-3b0e-44f3-a312-e7e877db2fb0}"
    }
  }
}