Poem Line Numbers

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "manifest_version": 3,
  "name": "Poem Line Numbers",
  "version": "0.6",
  "description": "Add line numbers to poems on PoetryFoundation.org",
  "permissions": [],
  "action": {
    "default_popup": "hello.html"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.poetryfoundation.org/*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "styles.css"
      ]
    }
  ]
}