Examine source code of Prolific @ Night

{
  "manifest_version": 2,
  "name": "Prolific @ Night",
  "description": "My eyes hurt everytime I see Prolific on my browser past 10pm. Here's something useful I made for you and me.",
  "version": "1.0",
  "author": "Jakub Michalak",
  "pozdrowienia": "dla wszystkich konfiaków",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "content_scripts": [
    {
      "css": [
        "styles.css"
      ],
      "matches": [
        "*://app.prolific.ac/*"
      ]
    }
  ],
  "browser_action": {
    "default_icon": {
      "20": "icon20.png",
      "40": "icon40.png"
    }
  },
  "applications": {
    "gecko": {
      "id": "prolificatnight@gumistudio.pl"
    }
  }
}