Responsive Image height

When you creat/edit the post/page, do not put the inline style in the <img />, you should just let whatever classes WP outputs by default.

In short, don’t hardcode the <img /> tag, just paste the image via WP’s post editor normally, and the problem will go away, your image will scale proportionally.

BTW, your theme is a commercial one, it has its own dedicated support forum.