Shit slider

First shit slider

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/hammer.js/2.0.8/hammer.min.js"></script>
<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<meta http-equiv="X-UA-Compatible" content="ie=edge">
	<link rel="stylesheet" href="/style.css">
	<title>Document</title>
</head>
<body>

<a href='#' class='modal_link' id='m1'>form 1</a>
<a href='#' class='modal_link' id='m2'>form 2</a>

  <div class='m1 modal'>
  <p>form 1</p>
    <form method="post" action="form.php">
        <input type="text" name="name" required>
        <input type="email" name="email" required>
        <button type="submit">Отправить</button> 
    </form>     
  </div>
  
  <div class='m2 modal'>
  <p>form 2</p>
    <form method="post" action="form.php">
        <input type="text" name="name2" required>
        <input type="email" name="email2" required>
        <button type="submit">Отправить</button> 
    </form> 
  </div>

	<script src="/script.js"></script>
</body>
</html>

CSS

body {
  margin: 0;
  padding: 0px;
  
}

* {
  box-sizing: border-box;
}

.modal {
  position: fixed;
  display: block;
  background: #ccc;
  max-width: 600px;
  margin-top: 10%;
  min-width: 260px;
  transform: translateY(-900px) scale(0.1,0.2);
  transition: 0.5s;
  text-align: center;
  opacity: 0;
  box-sizing: border-box;
  padding: 20px;
}

JavaScript

var els = document.getElementsByClassName('modal_link');
for(var i in els){
    els[i].addEventListener('click', function(e) {
    	
      tabcontent = document.getElementsByClassName(" modal");
      for (i = 0; i < tabcontent.length; i++) {
        	tabcontent[i].style.transform = "translateY(-900px) scale(0.1,0.2)";
        	tabcontent[i].style.opacity = "0";
      };
      
      var el = this.getAttribute('id');
      var el_box = document.querySelector('.'+el);
			el_box.style.marginLeft = 'calc(50% - '+(el_box.offsetWidth / 2)+'px)';
      el_box.style.marginRight = 'calc(50% - '+(el_box.offsetWidth / 2)+'px)';
      el_box.style.transform = "translateX(0px) scale(1,1)";
      el_box.style.opacity = "1";
	});
};