Recommended image size for image slider?

Can anyone provide a link for the recommended formatting for images used in an image slider? I’m getting different results on different pages (e.g., “project” page vs. “home” page in the example). In particular, one set of dimensions is getting cut off at the bottom, while the same image displays correctedly on a small cell phone. A search has not turned up a usable reference to “image slider” in the documentation. Thanks!