Aadya thumbnail widget incorrectly responsive

The image in thumbnail widgets is incorrectly resized when the whole page is resized (reduced). The image height remains constant but the width alters to fit the available width – resulting in the people in the photos getting very fat faces!

Do the settings allow any way of stopping this happening? I’ve tried Full, Thumbnail, etc for the image but it makes no difference. If I replace the Thumbnail widgets by Text widgets containing <img /> details then the photos remain the correct size, but it’s a pity not to be able to use your widget.

Thanks.