manifest.json

{
    "name": "CF-Dark Theme",
    "version": "0.1.0",
    "author": "Prashant (Prashant0664 on github)",
    "description": "Change Codeforces Theme",
    "permissions": ["tabs"],
    "host_permissions": ["https://codeforces.com/*"],
    "background": {
      "service_worker": "background.js"
    },
    "content_scripts": [
      {
        "matches": ["https://codeforces.com/*"],
        "js": ["contentScript.js"],
        "css": ["popup.css"]
      }
    ],
    "web_accessible_resources": [
        {
            "resources": [
            "icons/bookmark.png",
            "icons/play.png",
            "icons/delete.png",
            "icons/save.png"
          ],
        "matches": ["https://codeforces.com/*"]
      }
    ],
    "action": {
      "default_icon": {
        "16": "icons/apple-touch-icon.png",
        "24": "icons/apple-touch-icon.png",
        "32": "icons/apple-touch-icon.png"
      },
      "default_title": "CF_Dark Theme",
      "default_popup": "popup.html"
    },
    "externally_connectable": {
      "matches": ["https://codeforces.com/*"]
    },
    "manifest_version": 3
  }