Включите jQuery
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
</head>
Attractive Albatross
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
</head><!--You can insert Jquery into HTML with the <script> tag in the <head>-->
<!--Insert the next line of code into your <head> tags.-->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script> <!-- jquery (help with javascript) -->