Oh, thank you so much for getting back with me! This has been a problem for me for a long time. I figured it was just an issue with squarespace, so I've always just been aggravated... but excepting it as it was. Today, I had a post where it happened to 6/10 images. And I decided to look for an answer.
To better explain the issue. I don't think it's a css problem or an image size problem. I upload images that are always larger than our post width. Our post width is 770px. And our images are usually around 1000px wide.
If you look at this post (which is just a roundup of instagrammers)... http://www.theshelf.com/blogger-roundups/australian-bloggers The first 6 images are scaled down to exactly 720px wide. While the last 4 maintain the original dimensions of the image that was uploaded.
Why would those first 6 get resized, while the last 4 are not? The last 4 fit beautifully at 100% the width of the post (770px)... while the rest of the images (the six that were scaled down to 720px) throw off the layout. For no reason other than the platform seems to just arbitrarily choose some images to scale, while leaving others untouched.
Any help with this would be great!