RewriteEngine On
RewriteBase /_frontend/

RewriteRule ^index\.html$ - [L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]

RewriteRule ^ index.html [L]

<Files "index.html">
    Header set Cache-Control "no-cache, no-store, must-revalidate"
    Header set Pragma "no-cache"
    Header set Expires 0
</Files>