Examine source code of Social Media Grayscale

{
  "manifest_version": 3,
  "name": "Social Grayscale",
  "version": "1.0.0",
  "description": "Renders matched social media sites in grayscale. No scripts, no tracking, no storage.",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "social-grayscale@andregallant.local",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://facebook.com/*",
        "*://*.facebook.com/*",
        "*://fb.com/*",
        "*://*.fb.com/*",
        "*://youtube.com/*",
        "*://*.youtube.com/*",
        "*://youtu.be/*",
        "*://*.youtu.be/*",
        "*://youtube-nocookie.com/*",
        "*://*.youtube-nocookie.com/*",
        "*://instagram.com/*",
        "*://*.instagram.com/*",
        "*://tiktok.com/*",
        "*://*.tiktok.com/*",
        "*://reddit.com/*",
        "*://*.reddit.com/*",
        "*://old.reddit.com/*",
        "*://*.old.reddit.com/*",
        "*://truthsocial.com/*",
        "*://*.truthsocial.com/*",
        "*://twitter.com/*",
        "*://*.twitter.com/*",
        "*://x.com/*",
        "*://*.x.com/*",
        "*://threads.net/*",
        "*://*.threads.net/*",
        "*://threads.com/*",
        "*://*.threads.com/*",
        "*://bsky.app/*",
        "*://*.bsky.app/*",
        "*://linkedin.com/*",
        "*://*.linkedin.com/*",
        "*://pinterest.com/*",
        "*://*.pinterest.com/*",
        "*://snapchat.com/*",
        "*://*.snapchat.com/*",
        "*://tumblr.com/*",
        "*://*.tumblr.com/*",
        "*://twitch.tv/*",
        "*://*.twitch.tv/*",
        "*://kick.com/*",
        "*://*.kick.com/*",
        "*://discord.com/*",
        "*://*.discord.com/*",
        "*://mastodon.social/*",
        "*://*.mastodon.social/*",
        "*://mstdn.social/*",
        "*://*.mstdn.social/*",
        "*://pixelfed.social/*",
        "*://*.pixelfed.social/*",
        "*://flickr.com/*",
        "*://*.flickr.com/*",
        "*://medium.com/*",
        "*://*.medium.com/*",
        "*://quora.com/*",
        "*://*.quora.com/*",
        "*://nextdoor.com/*",
        "*://*.nextdoor.com/*",
        "*://vk.com/*",
        "*://*.vk.com/*",
        "*://ok.ru/*",
        "*://*.ok.ru/*",
        "*://weibo.com/*",
        "*://*.weibo.com/*",
        "*://weibo.cn/*",
        "*://*.weibo.cn/*",
        "*://xiaohongshu.com/*",
        "*://*.xiaohongshu.com/*",
        "*://xhslink.com/*",
        "*://*.xhslink.com/*",
        "*://lemon8-app.com/*",
        "*://*.lemon8-app.com/*",
        "*://bereal.com/*",
        "*://*.bereal.com/*",
        "*://clubhouse.com/*",
        "*://*.clubhouse.com/*",
        "*://gab.com/*",
        "*://*.gab.com/*",
        "*://gettr.com/*",
        "*://*.gettr.com/*",
        "*://parler.com/*",
        "*://*.parler.com/*",
        "*://rumble.com/*",
        "*://*.rumble.com/*",
        "*://substack.com/*",
        "*://*.substack.com/*",
        "*://patreon.com/*",
        "*://*.patreon.com/*",
        "*://messenger.com/*",
        "*://*.messenger.com/*",
        "*://web.whatsapp.com/*",
        "*://*.web.whatsapp.com/*",
        "*://telegram.org/*",
        "*://*.telegram.org/*",
        "*://t.me/*",
        "*://*.t.me/*"
      ],
      "css": [
        "grayscale.css"
      ],
      "run_at": "document_start",
      "all_frames": true,
      "match_about_blank": true,
      "css_origin": "user"
    }
  ]
}