If I am understanding your concern correctly, it looks like you have a couple of issues causing this problem.
On your base breakpoint, you are manually setting the height of your image. This is causing the image to become larger than it’s container becasue you are forcing the size.
To fix this on your main break point, you can chance the slider to 100%, however, I would recommend making the image 100% height instead of px.
In your smaller break points, you have a margin set as -## on your slider image. This is causing the image to be pulled above the slider itself.
I hope this helps, let me know if you have any additional issues.