title: htaccess add .php to everything without an extension already
body: <p>I'm looking around SO for duplicates, but I'm having trouble finding what I think should be a simple answer.</p>
  
  <p>What are the rewrite rules to add <code>.php</code> to anything without an extension already?</p>
  
  <p>examples:</p>
  
  <p>www.website.com/styles.css -> www.website.com/styles.css</p>
  
  <p>www.website.com/login -> www.website.com/login.php</p>
  
  <p>THANKS!</p>