Examine source code of Youtube Theme Engine

{
  "manifest_version": 3,
  "name": "Youtube Theme Engine",
  "version": "1.1.2",
  "description": "A private theme, layout, media, focus, and accessibility engine for YouTube and YouTube Music.",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png",
    "512": "icons/icon-512.png"
  },
  "action": {
    "default_popup": "popup/action.html",
    "default_title": "Youtube Theme Engine",
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "96": "icons/icon-96.png"
    }
  },
  "sidebar_action": {
    "default_panel": "popup/sidebar.html",
    "default_title": "Youtube Theme Engine",
    "default_icon": {
      "48": "icons/icon-48.png",
      "96": "icons/icon-96.png"
    },
    "open_at_install": false
  },
  "permissions": [
    "storage"
  ],
  "background": {
    "scripts": [
      "shared/themes.js",
      "background/background.js"
    ]
  },
  "commands": {
    "toggle-theme-engine": {
      "suggested_key": {
        "default": "Ctrl+Shift+Y"
      },
      "description": "Pause or resume Youtube Theme Engine"
    },
    "toggle-zen-mode": {
      "suggested_key": {
        "default": "Ctrl+Shift+U"
      },
      "description": "Toggle distraction-free Zen mode"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://youtube.com/*",
        "https://www.youtube.com/*",
        "https://m.youtube.com/*",
        "https://music.youtube.com/*",
        "https://www.youtube-nocookie.com/embed/*"
      ],
      "js": [
        "shared/themes.js",
        "shared/engine.js",
        "content/content.js"
      ],
      "run_at": "document_start",
      "all_frames": true
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "youtube-theme-engine@rob.projects",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  }
}