Custom .htaccess maintenance mode

.htaccess

<IfModule mod_rewrite.c>
 RewriteEngine on
 # Customize specific IP address which should have access to the live site
 RewriteCond %{REMOTE_ADDR} !^11\.22\.33\.44
 
 # Customize name of your maintenance mode template file
 RewriteCond %{REQUEST_URI} !/maintenance.html$ [NC]
 
 # Only images and CSS files are allowed.  Customize to allow Javascript or other image extensions
 RewriteCond %{REQUEST_URI} !\.(jpe?g?|png|gif|css) [NC]
 
 # Customize name of your maintenance mode template file
 RewriteRule .* /maintenance.html [R=302,L,E=nocache:1]
 
 # Set the response header if the "nocache" environment variable is set in the RewriteRule above.
 Header always set Cache-Control "no-store, no-cache, must-revalidate" env=nocache
 Header always set Expires "Thu, 01 Jan 1970 00:00:00 GMT" env=nocache
</IfModule>