RewriteEngine On
AddType text/css .css
RewriteCond %{HTTPS} off
RewriteCond %{HTTP_HOST} ^www\. [NC]
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

# redirect http(s)://example.com to https://www.example.com
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^ https://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

RewriteRule . index.php [L]