Examine source code of Blue Spotify

{
  "name": "Blue Spotify",
  "optional_host_permissions": [
    "https://open.spotify.com/"
  ],
  "description": "spotify theme",
  "manifest_version": 3,
  "version": "1.0.1",
  "host_permissions": [
    "https://open.spotify.com/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{ac8c60bf-3e85-44dd-b454-0be7f219ed3f}",
      "data_collection_permissions": {
        "required": [
          "browsingActivity"
        ]
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://open.spotify.com/*"
      ],
      "js": [
        "Content.js"
      ],
      "css": [
        "firefox.css"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "images/theme_1.png",
        "images/bg.png",
        "images/bg4.png",
        "Fonts/Dacherry.ttf",
        "images/bg5.png",
        "images/left.png",
        "images/middle.png",
        "images/right.png"
      ],
      "matches": [
        "https://open.spotify.com/*"
      ]
    }
  ],
  "icons": {
    "16": "16blue_spotify.png",
    "32": "32blue_spotify.png",
    "48": "48blue_spotify.png",
    "128": "128blue_spotify.png"
  }
}