Q:

How to set a div to change its background and alpha levels upon scrolling

I am looking at websites for inspiration for my new start ups homepage. I saw https://www.pactcoffee.com/ and their home page features a full background image for the header and the nav bar is transparent then it becomes a solid color nav bar as you scroll down. I have only been able to set up the CSS for the site but I don't understand what to do to have the change in nav bar color.

A:

You can do something like this...
http://jsfiddle.net/ojcqbLr2/
Check the Fiddle to see the rest of the code... like the CSS.
This JS will do this.
$(document).scroll(function () {
var y = $(this).scrollTop();
if (y > 100) {
    $('.topMenu').fadeIn();
} else {
    $('.topMenu').fadeOut();
} });

By the way, I found this info by search. 
Show div on scrollDown after 800px
I just made edits to the code so it was at the top and not bottom.
Best of luck.

