Make image previews keep aspect ratio of original, and larger max size.

brutaldon/static/css/brutaldon.css

@@ -29,6 +29,16 @@ div.card-header-title, div.card-header-icon {
     margin-top: 0.75rem;
 }
 
+.is-max-128 {
+    max-height: 128px;
+    max-width: 128px;
+}
+
+.is-max-256 {
+    max-height: 256px;
+    max-width: 256px;
+}
+
 figure.media-left p.image a img
 {
     border-radius: 5px;

brutaldon/templates/main/toot_partial.html

@@ -71,7 +71,7 @@
                                      {% if media.description %}
                                      title="{{ media.description }}"
                                      {% endif %}
-                                     class="image is-128x128">
+                                     class="image is-max-256">
                         </a>
                     {% endfor %}
                 </div>