"hanging the element of the page of the top" problem

Hello;

I have several problems in a same situation.

1. When entering in mobile device to this page (link1), the purchase element is hanging in the top of the page in layout element and don’t let visitors see the other elements. I want it stays in the desktop pages but not hanging in the mobiles. How can I do that?
2. When entering in the same page via desktop and we slip the page down, the purchase element gets out of the layout element and gets transparent. Can we make it always stays in the layout element when we slip the page?
3. When I put another content element in the layout element like in this page(link2) (other then purchase button). Hanging In the top of the page situation gets inactive. how can I use this layout element always does its hanging function with all content elements?

– By the way, I inspired this page design via this website (link3). Maybe it helps you to understand what I am trying to ask.

Thanks for your kindly helps & Happy new year