.htaccess

<IfModule mod_rewrite.c>
RewriteEngine on

# ========================================================
# ====  Uncomment to check if .htaccess is working  ======
# RewriteRule ^.*$ htaccess_tester.php
# ========================================================

# ========================================================
# ====  for assets files =================================
# Rewrite if the file does not exists
RewriteCond %{REQUEST_FILENAME} !-f
# Rewrite only if the URI does not starts with assets
RewriteCond %{REQUEST_URI} !^/assets
# Rewrite any assets file
RewriteRule ([^/]*).(css|js|png|jpe?g)$ assets/$1.$2 [L]
# ========================================================

# ========================================================
# ====  for index.php rewrite  ===========================
# Rewrite if the file does not exists
RewriteCond %{REQUEST_FILENAME} !-f
# Rewrite if the directory does not exists
RewriteCond %{REQUEST_FILENAME} !-d
# Rewrite to add index.php
RewriteRule ^(.*)$ index.php?/$1 [L]
# ========================================================

</IfModule>