background CSS code to change the pan direction on background image 7.1

Hello,

I design in 7.0 and am experimenting with 7.1. I would like to create a parallax effect using the "pan" on background images. I'm trying to create movement and depth with the background image moving from left to right - it looks like I can pan from left to right - but not right to left.

How can I make the background image move from right to left on specifically chosen pages if I want to create this movement.

Thank you kindly,

Rebecca

I would love to be able to choose the pan direction too...