Sticky Selections Bar for Fixed Right Side Total Bundle Theme

I’m using the fixed right side total bundle theme, and I’d love to have the selections bar stay sticky at the TOP of the screen while customers scroll.

Having it fixed would make the experience feel more seamless and interactive, almost like the Crumbl cookie app. It would really help customers keep track of their bundle as they browse, making it easier to complete their selections without scrolling back up.

Note: Current design is the "Order details" box is only sticky at the right side.