Internet Explorer issue

Hello, I’ve a problem with one thing. As you can see, if you’re on the main page and you scroll down, the truck is fixed and it makes an effect with the background. Is’s done by using the multiply effect on background overlay. It’s everything okay, expect that it’s not working on the internet explorer. On the internet explorer, all what you see is the background overlay so you don’t see this truck. What I think is just that the multiply effect doesn’t work on the internet explorer. I don’t know if I’m true, but if you guys can tell me how I can reassure such effect not using the multiply effect or is there other solution. I think maybe I can apply CSS only for IE and I would set overlay opacity on about 0.3? But I don’t have idea how can I apply such CSS.
I know that no one is using this explorer, but my client is, and he wants to make it works.

Thank you very much in advance! 🙂

The page I need help with: [log in to see the link]