Improve styling of match references and match trees

Change-Id: Ibd09352dc4b825e147e83ee5c97fa87e8d5082d4
diff --git a/dev/scss/main/view/matchtree.scss b/dev/scss/main/view/matchtree.scss
index 96fb86a..4f5edbc 100644
--- a/dev/scss/main/view/matchtree.scss
+++ b/dev/scss/main/view/matchtree.scss
@@ -41,4 +41,9 @@
     margin-right:     $right-view-distance;
     background-color: $light-orange;
   }
+
+  svg {
+    overflow: visible;
+    margin: 1em;
+  }
 }