server {
  listen 80;
  root /usr/share/nginx/html;
  index index.html;
  # HTML must revalidate every load — deploys were invisible behind
  # browser cache. Images/banners keep default caching.
  location = /index.html { add_header Cache-Control "no-cache"; }
  location = / { add_header Cache-Control "no-cache"; try_files /index.html =404; }
}