Maybe/app/views/pwa/manifest.json.erb

{
  "name": "Maybe",
  "short_name": "Maybe",
  "icons": [
    {
      "src": "/icon.png",
      "type": "image/png",
      "sizes": "512x512"
    },
    {
      "src": "/icon.png",
      "type": "image/png",
      "sizes": "512x512",
      "purpose": "maskable"
    }
  ],
  "start_url": "/",
  "display": "standalone",
  "display_override": ["fullscreen", "minimal-ui"],
  "scope": "/",
  "description": "Maybe.",
  "theme_color": "#ffffff",
  "background_color": "#ffffff"
}