Why are my 300×300 images stretching?

It seems you have an inline style setting a minimum height for images. See https://dl.dropboxusercontent.com/1/view/7ss3a79ds0dd4m1/Apps/Shutter/Selection_001.png?dl=0

Please disable all plugins and see if the problem goes away. If so, re-enable them one at a time until you find what’s doing it.

If not, then it’s the theme. You might ask the theme developers why that’s there…
https://theme4press.com/support-forums/

Thanks for your response. I’ve disabled all plugins and it’s still stretching my images. I’m unable to ask the developers as I only have a free account. Can anyone else help with this problem?