<?php

$errors = array();
if(isset($_POST['submit']))
{

    if(empty($_POST['username']))
    {
        $errors[] = "Username is empty!";
    }
    else
    {
        $username = $_POST['username'];
        setcookie('username', $username, $expiry->getTimestamp());
    }
    if(empty($_POST['password']))
    {
        $errors[] = "Password is empty!";
    }
    else
    {
        $password = $_POST['password'];
        setcookie('password', $password, $expiry->getTimestamp());
    }

    $expiry = new Datetime('+1 year');


    echo $_COOKIE['username'].", ".$_COOKIE['password'];
}
?>
<form action="#" method="post">
    <label for="username">Username: </label><input type="text" name="username"><br />
    <label for="password">Password: </label><input type="text" name="password"><br />
    <input type="submit" name="submit" value="Submit">
</form>
<div class="parent">
    <?php
        if(!empty($_COOKIE)) {
            echo $_COOKIE['username'].", ".$_COOKIE['password'];
        }
        else {
            echo "<ul>"
            foreach($errors as $error)
            {
                echo "<li>".$error."</li>";
            }
            echo "</ul>";
        }
    ?>
</div>
<style>
    .parent {
        background-color: red;
        width: 500px;
        height: 500px;
        text-align: center;
        line-height: 500px;
    }
</style>