CSS not rendering on multisite subfolders

I'm trying to set up a WP multisite using subfolders on a mac mini. I set everything up automatically using the bitnami multisite installer, and the main site seems to be functioning perfectly. The problem is all other sites, which are in subfolders, are rendering without any CSS.

I've done a lot of reading on this and people seem to say it's related to the .htaccess file, which I've modified according to the instructions in network setup for subfolders. I've also pasted it below:

# BEGIN WordPress
AllowOverride FileInfo Options All

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

RewriteCond %{REQUEST_FILENAME} -s [OR]
RewriteCond %{REQUEST_FILENAME} -l [OR]
RewriteCond %{REQUEST_FILENAME} -d

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|includes).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]
# END WordPress

I've also set the the wp-config site as requested:

define( 'SUBDOMAIN_INSTALL', false );
$base = '/';
define( 'DOMAIN_CURRENT_SITE', 'wordpress.standrews-de.org' );
define( 'PATH_CURRENT_SITE', '/' );
define( 'SITE_ID_CURRENT_SITE', 1 );
define( 'BLOG_ID_CURRENT_SITE', 1 );

Here is an example of one of the errors the site reports when trying to load css files:

Failed to load resource: the server responded with a status of 404 (Not Found)

http://wordpress.standrews-de.org/jburk/wp-includes/js/jquery/jquery-migrate.min.js?ver=1.2.1

Any help would be most appreciated.