#mainbody{ 
	min-width:980px;
	max-width:1190px;
	margin:0 auto;
} 

.postattachlist { width:100%; } /* change existing class to width:100% (@style_1.css) */
.postattachlist .t_attachlist dd p img { max-width:100%; }

.t_msgfont img {max-width:100%; height:auto;}