Examine source code of ProtonDB for Steam

{
  "manifest_version": 2,
  "version": "1.3",
  "name": "ProtonDB for Steam",
  "description": "Adds the ProtonDB rating to games in the Steam store so you get an idea of how it will run before you buy it!",
  "permissions": [
    "https://www.protondb.com/*"
  ],
  "background": {
    "page": "js/background.js"
  },
  "icons": {
    "16": "/icons/proton_16.png",
    "32": "/icons/proton_32.png",
    "48": "/icons/proton_48.png",
    "128": "/icons/proton_128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://store.steampowered.com/app/*"
      ],
      "js": [
        "js/steamStore.js"
      ],
      "css": [
        "css/protondbCard.css"
      ]
    },
    {
      "matches": [
        "https://store.steampowered.com/search*"
      ],
      "js": [
        "js/steamSearch.js"
      ],
      "css": [
        "css/protondbCard.css"
      ]
    }
  ]
}