Shadow under website header

Site URL: https://www.huntersgaragepa.com/

Hi! I need some help to make a shadow under the website header of my website that shows itself once the user starts scrolling. I would like if it disappeared when the user goes back to the top of the page. 

If you can help me, I would be very thankful.

What inspired this was the website header for Juniper Books.

22 hours ago, huntersgaragellc said:

Site URL: https://www.huntersgaragepa.com/

Hi! I need some help to make a shadow under the website header of my website that shows itself once the user starts scrolling. I would like if it disappeared when the user goes back to the top of the page. 

If you can help me, I would be very thankful.

What inspired this was the website header for Juniper Books.

 

try

header.shrink {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 100;
    box-shadow: 0 0 16px 0 rgb(0 0 0 / 50%);
}