Codeforces Zen mode

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Codeforces Zen mode",
  "description": "",
  "version": "1.1",
  "manifest_version": 3,
  "action": {
    "default_icon": {
      "16": "/images/16.png",
      "32": "/images/32.png",
      "48": "/images/48.png",
      "64": "/images/64.png",
      "128": "/images/128.png"
    }
  },
  "content_scripts": [
    {
      "run_at": "document_end",
      "matches": [
        "http://*.codeforces.com/*",
        "https://*.codeforces.com/*"
      ],
      "css": [
        "style.css"
      ]
    }
  ]
}