wp_head not injecting css

Your php code block is not properly formated.
You currently have this


Notice the opening php tag <php?, a correct php tag is <?php.
A less than symbol < followed by a question mark ? followed by the word php.
So a proper php block would look like this

    // Your code here

There are others you can check out in the official documentation, https://www.php.net/manual/en/language.basic-syntax.phptags.php