Issues w/ Images on Blog Page

Site URL: http://conductor.solar/blog

Hello, I'm trying to address how preview images are displayed on my site's blog page - Squarespace's resizing makes small images way too big, and big images can't be viewed in full. 

Is there a way to 1) make the preview images smaller, and/or 2) ensure they are resized consistently?

It would be easier if all the images I planned on uploading shared dimensions/resolutions, but they're going to be varied. Thank you!

Try adding to Design > Custom CSS > then save & reload the site

.blog-single-column .image-wrapper {
    width: 50%;
    margin: 0 auto;
}