Examine source code of UX by Xavi

{
  "description": "Improves the readability and user experience on websites",
  "manifest_version": 2,
  "name": "UX by Xavi",
  "version": "1.0.9",
  "homepage_url": "https://xaviesteve.com/",
  "browser_specific_settings": {
    "gecko": {
      "id": "{0d222680-3072-4674-b9ff-39f476cc1db5}",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "48": "icon-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.atlassian.net/jira/software/projects/*"
      ],
      "js": [
        "jira.atlassian.net/script.js"
      ],
      "css": [
        "jira.atlassian.net/style.css"
      ]
    },
    {
      "matches": [
        "https://news.ycombinator.com/*",
        "https://hn.algolia.com/*"
      ],
      "js": [
        "news.ycombinator.com/script.js"
      ],
      "css": [
        "news.ycombinator.com/style.css"
      ]
    },
    {
      "matches": [
        "https://*.slack.com/client/*"
      ],
      "js": [
        "slack.com/script.js"
      ],
      "css": [
        "slack.com/style.css"
      ]
    }
  ]
}