Access third_party folder

Hello,

I am trying to add foundation css folder to my project under "third_party" folder but, I get an error depending on the path.

Permissions are normal : rwxrwxr-x for folder and sub folders in third _party

Server: Apache 

Path: "//mysite.com/application/third_party/foundation-6.4.2/css/app.css" gives a 404

Path: "href="<?php echo base_url(); ?>third_party/foundation-6.4.2/css/app.css" gives "Refused to apply style from 'https://mysite.com/third_party/foundation-6.4.2/css/app.css' because its MIME type ('text/html') is not a supported stylesheet MIME type, and strict MIME checking is enabled."

if moved to www/CI/assets/foundation I can access it just fine, but why can't I access anything in third_party ?


********** Edit add 12:53PM MT **************
.htaccess file
RewriteCond $1 !^(index\.php|assets|images|js|css|uploads|favicon.png)
RewriteCond %(REQUEST_FILENAME) !-f
RewriteCond %(REQUEST_FILENAME) !-d
RewriteRule ^(.*)$ index.php?/$1 [L,QSA]