firebase.json

{
  "firestore": {
    "rules": "firestore.rules",
    "indexes": "firestore.indexes.json"
  },
  "hosting": {
    "public": "build",
    "headers": [
      {
        "source": "**/*",
        "headers": [
          {
            "key": "X-Content-Type-Options",
            "value": "nosniff"
          },
          {
            "key": "X-Frame-Options",
            "value": "DENY"
          },
          {
            "key": "X-UA-Compatible",
            "value": "ie=edge"
          },
          {
            "key": "X-XSS-Protection",
            "value": "1; mode=block"
          }
        ]
      },
      {
        "source": "**/*.@(css|html|js|map)",
        "headers": [
          {
            "key": "Cache-Control",
            "value": "max-age=3600"
          }
        ]
      }
    ],
    "rewrites": [
      {
        "source": "**",
        "destination": "/index.html"
      }
    ]
  }
}