fix images not being scaled to fit parent.

svelte-ui/src/components/Markdown.svelte

@@ -35,6 +35,10 @@
     margin: 0.5em 0;
   }
 
+  div.markdown :global(img) {
+    width: 100%;
+  }
+
   div.markdown :global(ol), div.markdown :global(ul) {
     padding: 0.5em;
     margin: 0.25em 0;