Its better to use filter_input

For line 30 31 and 31 Login.php

// The parameter values 
        $query_params = array( 
            ':username' => $_POST['username'] 
        ); 

I think you should use

$name = filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING);
$query_params = array( 
            ':username' => $name
        ); 

and also add example for cookies management