horizontal scroll bar on mobile

When I put a post carousel on my website it messes up the display on the mobile version of the website (you can see it on the desktop version as well by making the browser very narrow). There’s a gray stripe down the entire right side of the page (you can see it if you scroll the browser to the right side). This gray stripe contains the navigation arrow for the carousel.

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