Modify responsive burger menu icon

Hello,

I would like to change the code of the responsive menu to look like this: codepen.io/designcouch/pen/Atyop

I am searching with keywords in the template .php files but cannot find the file (but the menu .js file) that manages that.

I would like to change the default <a href="#" class="nav-toggle" aria-hidden="false">Menu</a> to

<a href="#" class="nav-toggle" aria-hidden="false">
<div id="nav-icon">
<span></span>
<span></span>
<span></span>
</div>
</a>

Is this possible and where?

Thanks.

Copying of features from web sources to existing Joomla templates requires good Joomla and programming knowledge. We can't support that. We can only do it on your behalf for a fee.

Thanks,
Milos