<div id="id00" class="login">
    <form class="modal-content animate" action="chat1.php" method="POST">
        <div class="cross">
            <span onclick="document.getElementById('id01').style.display='none'" class="close" title="Close Modal">&times;</span>
        </div>
        <div class="form">
            <label><b>Username</b></label>
            <input type="text" placeholder="Enter Username" name="username" required>
            <label><b>Password</b></label>
            <input type="password" placeholder="Enter Password" name="password" required>
            <button type="submit">submit</button>
        </div>
    </form>
</div>

<?php
    ob_start();
    $username = "root";
    $password = "";
    $hostname = "localhost";
    $dbname = "login";
    $dbhandle = mysqli_connect($hostname, $username, $password, $dbname) or die("unable to connect to MySQL");
    if(isset($_POST["username"],$_POST["password"]))
    {
        $user = $_POST["username"];
        $pass = $_POST["password"];
        $result1 = mysqli_query("SELECT password FROM login WHERE username = '".$user."'");
        $result2 = mysqli_query("SELECT username FROM login WHERE password = '".$pass."'");
        if($user == $result2 && $pass == $result1)
        {
            $_SESSION["logged_in"] = true;
            $_SESSION["naam"] = $name;
        }
        else
        {
            echo "incorrect username/password";
        }
    }
?>

enter code here