How to hide div class in css - html

Question

On clicking submit button how to hide the below div class. I have tried >with div id but div class is not working as exactly as div id. As I have
written the code but It was closing entire window. Below is the code without adding jquery.
<div class="w3-container w3-light-grey w3-padding-32 w3-padding-large" id="contact">
<div class="w3-content" style="max-width:600px">
<h4 class="w3-center"><b>Please fill the form to continue</b></h4>
<script type="text/javascript">var submitted=false;</script>
<!--Update the URL for thank you page on form submit -->
<iframe name="hidden_iframe" id="hidden_iframe" style="display:none;"
onload="if(submitted) {window.location='';}"></iframe>
<!-- Update the Google forms URL in action-->
<form class= 'form1' action="https://docs.google.com/forms/u/0/d/a/1FAIlQLDFDHBaSVqkaf1BLTQ1MeRa1NH8OGw4Tpj_SZUvRj-QUTYu9Qw/formResponse" method="post" target="hidden_iframe" onsubmit="return validateForm(); ">
<div class="w3-section">
<label>Name</label>
<input class="w3-input w3-border" type="text" placeholder="Name" id="name" required name="entry.482263238">
</div>
<div class="w3-section">
<label>Email</label>
<input class="w3-input w3-border" type="text" placeholder="Email" id="email" required name="entry.227786006">
</div>
<div class="w3-section">
<label>Phone</label>
<input class="w3-input w3-border" type="text" placeholder="Phone" id="phone" required name="entry.30499006">
</div>
<div class="w3-section">
<button class="w3-button w3-block w3-black w3-margin-bottom" type="submit">submit</button>
</div>
</form>
</div>
</div>

Answer 1

In case you want to hide the entire form, you can add form.style.display = "none" to your validateForm() function:
const form = document.querySelector(".w3-container");
function validateForm() {
form.style.display = "none";
}
The same methodology applies if you want to hide some other div, just select it and apply element.style.display = "none";.
JSfiddle: Link