Options +FollowSymLinks -MultiViews
RewriteEngine On
RewriteBase /

RewriteCond %{HTTPS} !=on
RewriteRule ^(.*) https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
Header always set Content-Security-Policy "upgrade-insecure-requests;"

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.html -f
RewriteRule ^(.*)$ $1.html [L]

RewriteCond %{THE_REQUEST} ^(?:GET|POST)\ /.*\.html\ HTTP.*$ [NC]
RewriteRule ^(.*)\.html$ $1 [R=301,L]