Examine source code of e621 responsive

{
  "manifest_version": 2,
  "name": "e621 responsive",
  "version": "1.7",
  "description": "Makes e621 responsive.",
  "icons": {
    "48": "icon.png"
  },
  "content_scripts": [
    {
      "run_at": "document_idle",
      "matches": [
        "*://*.e621.net/*"
      ],
      "js": [
        "e621responsive.js"
      ]
    },
    {
      "run_at": "document_start",
      "matches": [
        "*://*.e621.net/*"
      ],
      "css": [
        "e621responsive.css"
      ]
    }
  ]
}