Images under attached images do not resize

[Edman]

I'm having a really weird problem.

I run a photo site, we don't use thumbnails, so its really important that large pictures uploaded are resized to browser width.

If I upload a picture and insert it into the post, it will resize correctly as I resize the browser.

		<div class="content">
			<div id="post_message_639120">
<blockquote class="postcontent restore">
sdgfadgfadgfadfg<img src="http://forum.fourthirdsphoto.com/attachment.php?attachmentid=49911&amp;d=1467730308" border="0" alt="Name:  15-07-01-21-24-40_P7012441.JPG
Views: 8
Size:  570.1 KB"  style="float: CONFIG" />
</blockquote>
			</div>

			


		</div>

If I upload a picture and then leave it there without adding it to the post, it appears in a box, and the picture won't resize

		<div class="content">
			<div id="post_message_639120">
<blockquote class="postcontent restore">
sdgfadgfadgfadfg
</blockquote>
			</div>

			
			<div class="attachments">

			

			
				<fieldset class="postcontent">
					<legend><img title="Attached Images" src="images/misc/paperclip.png" class="inlineimg" alt="Attached Images"> Attached Images</legend>
					<img class="attach" src="attachment.php?attachmentid=49911&amp;stc=1&amp;d=1467730308" alt="">&nbsp;
				</fieldset>


			</div>
			<!-- / attachments -->
			


		</div>

Instead of resizing, under the post, a navigation bar appears.

You can check the attached images to see the difference.

Tried changing to default skin, no change.

Any ideas?