How to change form on click?

Question

PHP

I made 2 forms (login and registration ) :
Zhmyak

Answer 1

index.php from line 21 replace with

<?php
    if($_SERVER["REQUEST_METHOD"] == "GET")
      if(isset($_GET["registration"]))
        require("parts/registr.php");
      else
        require("parts/login.php");
    ?>

login.php line 11 register.php line 12
<a href="?auth">Аuthorization</a>

Answer 2

jquery tabs

Answer 3

Because you didn't include js in the question tags...
https://codepen.io/aliencash/pen/wyXPwJ?editors=1100#0