<IfModule mod_rewrite.c>
#default
   RewriteEngine On
   RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /html/(.*).html\ HTTP/
   RewriteRule .* http://localhost/html/%1 [R=301,L]

   RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /html/(.*)\ HTTP/
   RewriteRule .* %1.html [L]


#custom
   RewriteCond %{REQUEST_FILENAME} !-f
   RewriteCond %{REQUEST_FILENAME} !-d
   RewriteCond %{REQUEST_FILENAME}.php -f

   RewriteRule ^(.+)$ $1.php [L,QSA]
   RewriteCond %{QUERY_STRING} ([^=]+)=([^=]+)

   RewriteRule ^/?$ %1/%2?  [L,R]
   RewriteCond %{REQUEST_FILENAME} !-f
   RewriteCond %{REQUEST_FILENAME} !-d
   RewriteCond %{REQUEST_FILENAME}.html -f
   RewriteRule ^(.+)$ $1.html [L,QSA]

</IfModule>