Carousel Banner Shows a Black Box Undernearth

Problem/Motivation

The carousel banner element's height doubles sometimes. When this happens, a black box appears under the banner, but disappears when you scroll to the next picture in the carousel.

Steps to reproduce

Create a Carousel Banner content container and add at least two banners. Some of the time, on page reload, or just randomly, a black box shows up below the carousel.

Proposed resolution

I don't know how to fix it, but so far I've tried:

- making sure all banners in the carousel have the same dimensions (no effect)
- setting the height of the element in css, and this fixed it, but then it's not responsive and the black box shows up permanently when the page dimensions change.

Expected behavior:
See noblackbox.png

What happens instead:
See blackbox.png