Strange behavior when checking %{REQUEST_FILENAME} in htaccess - .htaccess

Question

I'm confusing with my htaccess configuration. This is my site's structure:
\www
\public
\css
\js
In www directory, I have a htaccess like this:
RewriteEngine On
RewriteBase /
RewriteRule ^\.htaccess$ - [F]
RewriteCond %{HTTP_HOST} ^example\.com [NC]
RewriteRule ^(.*)$ http://www\.example\.com/$1 [R,L]
RewriteCond %{HTTP_HOST} ^www\.
RewriteCond %{REQUEST_URI} !^/public/.
RewriteRule ^(.*)$ /public/$1 [NC,L]
And this one is in public directory:
RewriteBase /public/
RewriteCond %{REQUEST_FILENAME} -s [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^(.*)$ - [NC,L]
When I access css directory, browser address bar will shows in 2 different ways:
www.example.com/css -> www.example.com/public/css/
www.example.com/css/ -> www.example.com/css/
Anyone can explain to me this difference and how can I configure to make both of them will return the second result www.example.com/css/

Answer 1

This is happening due to mod_dir adding a trailing slash after your rewrite rules. Have your root .htaccess like this:
RewriteEngine On
RewriteBase /
RewriteRule ^\.htaccess$ - [F]
RewriteCond %{HTTP_HOST} ^example\.com [NC]
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R,L,NE]
RewriteCond %{HTTP_HOST} ^www\.
RewriteCond %{DOCUMENT_ROOT}/$1 !-d [NC]
RewriteCond %{DOCUMENT_ROOT}/$1/ !-d [NC]
RewriteRule ^((?!public/).*)$ public/$1 [NC,L]