RewriteEngine On

DirectoryIndex index.html

<IfModule mod_headers.c>
#    Header set Alt-Svc "h3=':443'; ma=2592000,h3-29=':443'; ma=2592000"
    Header set Alt-Svc "h3=':443'"
</IfModule>

<IfModule mod_negotiation.c>
    Options -MultiViews
</IfModule>

RewriteCond %{ENV:REDIRECT_STATUS} ^$
RewriteRule ^index\.html(?:/(.*)|$) %{ENV:BASE}/$1 [R=301,L]

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

RewriteRule ^ %{ENV:BASE}/index.html [L]

