Hi,

1/ Unfortunately, currently this theme doesn't support this feature. We will consider to add more this feature in the future. The CSS can't do that.

2/ We need to crop the images to make it display good for all your layouts.

Example: Someone upload an image with size 500 x 5000 px - the height is very high with the width - And we can't display that image without crop it.

But, if you want to make so, please replace this code to this code:

\
<a class="penci-thumbnail-img <?php echo penci_class_lightbox_enable(); ?>" href="<?php penci_permalink_fix(); ?>" title="<?php echo wp_strip_all_tags( get_the_title() ); ?>">
 <?php the_post_thumbnail('penci-masonry-thumb'); ?>
</a>

Best Regards,

PenciDesign