Improve the user registration system to incorporate password hashing and salting techniques for enhanced security of user credentials.

<?php
    if (isset($_POST['submit'])) {
        require("connection.php");
        $email = $_POST['email'];
        $password = $_POST['password'];
        $re_password = $_POST['re-password'];
        $salt = "48@!alsd";
        $hash_password = hash_hmac('sha256', $password, $salt);
        if ($password == $re_password) {
            $sql = "INSERT INTO user_accounts (email, password) VALUES ('$email', '$hash_password')";
            $conn->query($sql);
            header("Location: login.php");
        } else {
            echo "Password does not match";
        }
        $conn->close();
    }
    ?>