Examine source code of Old Music Score

{
  "name": "Old Music Score",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "Old Music Score.jpg"
    },
    "colors": {
      "frame": "rgba(229, 230, 232, 1)",
      "tab_background_text": "rgba(242, 255, 56, 1)",
      "toolbar": "rgba(0, 0, 0, 0)",
      "toolbar_field": "rgba(0, 0, 0, 0.05)",
      "toolbar_field_text": "rgba(255, 230, 0, 1)",
      "tab_line": "rgba(252, 234, 75, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{50cf2461-94b6-46a6-87fe-742018d93a72}"
    }
  }
}