Keeping Aspect Ratio

I noticed that on mobile the aspect ratio for the slick slider is not maintained.

Here is a screenshot of how the slider looks on a regular desktop screen:

Here is how it looks on mobile:

You see how the image does not resize on a narrower screen? It cuts off some of the sides. How can I set it so that it resizes so that the entire image is visible on a narrower screen?

You can see the slider at the bottom of this page: https://hbcwr.ca

The shortcode I use is as follows:

[slick-carousel-slider category=”251″ slidestoshow=”3″ image_size=”original” centermode=”true” variablewidth=”true”]