@paul.r
This is almost working.
The link changes state if you manually scroll to the bottom of the page, but if you click on the Contact Us link the particle will appear and then be removed.
This is the code that I ended up with to target the correct menu items:
jQuery(function($) {
$(window).scroll(function() {
if($(window).scrollTop() + $(window).height() == $(document).height()) {
$('.x-particle.x-anchor-particle-primary').removeClass('x-active');
$('.menu-item-151 .x-particle.x-anchor-particle-primary').addClass('x-active');
} else if($(window).scrollTop() + $(window).height() > $(document).height() - 100){
$('.x-particle.x-anchor-particle-primary').removeClass('x-active');
$('.menu-item-150 .x-particle.x-anchor-particle-primary').addClass('x-active');
}else {
$('.menu-item-151 .x-particle.x-anchor-particle-primary').removeClass('x-active');
}
});
});
Here is the URL again: https://manmadecreative.com