I have the following Short-hand for a user profile url
RewriteRule ^(\\w+)/?$ ./profile.php?name_of_user=$1
The site is styled with the app
When you use this site.com/name_of_user/ you change the working directory on your site from root to name_of_user, therefore the relative path for each file or link on the requested page would become /name_of_user/ instead of /.
To fix this you need to add additional rule to .htaccess:
RewriteRule ^name_of_user/(.*)?$ $1