Add markdown utils

- External links open in a new tab
- Clicking on image open an image modal

resources/base.scss

@@ -923,4 +923,9 @@ input::placeholder{
         font-size: 22.5px;
         margin-right: 0.1em;
     }
+}
+
+.featherlight-content {
+    max-height: 80% !important;
+    border-radius: 10px;
 }