Fixed incorrect image aspect ratio when images have width/height attrs

no issue
- when large images have width/height attributes but the image is constrained to it's container or `max-width` style the aspect ratio would be broken because browsers use the `height` attribute value even though the width is smaller

assets/css/screen.css

@@ -842,6 +842,7 @@ The first (most recent) post in the list is styled to be bigger than the others
     display: block;
     margin: 1.5em auto;
     max-width: 1040px;
+    height: auto;
 }
 @media (max-width: 1040px) {
     .post-full-content img,