location ^~ /client/theme/ {
alias /www/wwwroot/www.youdomans.com/blesta/app/views/client/bootstrap/css/;
}
location ^~ /admin/theme/ {
alias /www/wwwroot/www.youdomans.com/blesta/app/views/admin/default/css/;
}
add this may be working.
/www/wwwroot/www.youdomans.com/ need change to yourself.