Hi there,
Let’s change your following code :
.x-colophon.bottom {
bottom: 0;
position: fixed;
width: 100%;
}
to this :
.x-colophon.bottom {
bottom: 0;
position: relative;
width: 100%;
}
.x-colophon.bottom.fixed-footer {
position: fixed;
}
Then add this under Custom > JavaScript in the Customizer.
jQuery(document).ready(function($) {
$(window).scroll(function() {
var scrollPos = $(window).scrollTop(),
footer = $('.x-colophon.bottom');
if (scrollPos > 300) {
footer.addClass('fixed-footer');
} else {
footer.removeClass('fixed-footer');
}
});
});
Hope this helps.
Cheers!