Want to hide sticky button on desktop and only show on mobile

Site URL: https://www.accorddental.ca/dental-office-near-me

I am having issues with adding a CTA sticky floating button that is on my landing page.  I would only like it to show up on my mobile page and not the desktop page.  How do I accomplish that and where do I insert code(and what code?). 

How I got to where I am:
In the advance part of the page in question I inserted the following code:

<div id="customFloatingButton">
    <a href="tel:12234533" target="_blank">Call Now</a>
</div>

<style>
    #customFloatingButton {
        position: fixed;
        bottom: 20px;
        right: 20px;
        z-index: 1000;
    }
    #customFloatingButton a {
        display: inline-block;
        background-color: #2952a3;
        color: white;
        padding: 15px 30px;
        text-decoration: none;
        box-shadow: 0px 5px 10px -5px rgba(0,0,0,0.5);
        transition: 200ms;
    }
    #customFloatingButton a:hover {
        transform: scale(1.04);
    }
</style>

How can I just make it just show up on the mobile only?
Thanks

11 hours ago, AlexJR said:

Site URL: https://www.accorddental.ca/dental-office-near-me

I am having issues with adding a CTA sticky floating button that is on my landing page.  I would only like it to show up on my mobile page and not the desktop page.  How do I accomplish that and where do I insert code(and what code?). 

How I got to where I am:
In the advance part of the page in question I inserted the following code:

<div id="customFloatingButton">
    <a href="tel:12234533" target="_blank">Call Now</a>
</div>

<style>
    #customFloatingButton {
        position: fixed;
        bottom: 20px;
        right: 20px;
        z-index: 1000;
    }
    #customFloatingButton a {
        display: inline-block;
        background-color: #2952a3;
        color: white;
        padding: 15px 30px;
        text-decoration: none;
        box-shadow: 0px 5px 10px -5px rgba(0,0,0,0.5);
        transition: 200ms;
    }
    #customFloatingButton a:hover {
        transform: scale(1.04);
    }
</style>

How can I just make it just show up on the mobile only?
Thanks

Add these code on Custom CSS panel in Website > Utilities > Website Tools > Custom CSS.

@media (min-width: 768px) {
    #customFloatingButton {
        display: none !important;
    }
}