Fixed linked images being micro on pdf export

Was caused by max-width: 100% causing confusion when images were
inside an anchor. This change resets that property on PDF
exports allowing full width images to be shown as so
without affecting smaller sizes.

Fixes #3120

resources/views/common/export-styles.blade.php

@@ -46,5 +46,9 @@
             clear: both;
             display: block;
         }
+
+        .page-content a > img {
+            max-width: none;
+        }
     </style>
 @endif