I'm having an issue here that looks kinda weird to me. Maybe it was already discussed a lot of times, but I couldn't find the right solution.
My posts on my site have images attached to them. Everything is fine here, but once I wanted to enlarge my content div a little bit, and everything is fitting fine, except the images. I get those stretchy, ugly images. The problem is surely not in the resolution because the width of the images I upload is about 900px, and the size I want them to enlarge to is somewhere near 800px. My theme by default is resizing them to ~400px and when I change the value to 800px, they get stretched, even if the image in the Media Library which I uploaded, is 900px.
How can I fix it? Please help.