Scrolling down the slider makes it change to gray

So whenever I scroll down my white-background slider, it changes into a gray background. I want to keep the slider at a white background throughout the scrolling downwards if that is possible. Not sure i’m explaining this well, so I added some pictures.

My site (www.jgsportstalk.com) is currently showing a static construction page.

Photo 1, the normal white background: https://s15.postimg.org/rxid4nf9n/Screen_Shot_2015_08_31_at_1_15_13_PM.png

Photo 2, as I start to scroll down the page, the white background turns gray: https://s15.postimg.org/azjcit5vv/Screen_Shot_2015_08_31_at_1_15_07_PM.png

Photo 3: https://s15.postimg.org/ll37utc7f/Screen_Shot_2015_08_31_at_1_15_20_PM.png