[Web] change opacity of footable collapse toggle

data/web/css/build/008-mailcow.css

@@ -232,6 +232,9 @@ table.footable>tbody>tr.footable-empty>td {
   font-style:italic;
   font-size: 1rem;
 }
+table>tbody>tr>td>span.footable-toggle {
+  opacity: 0.75;
+}
 .navbar-nav > li {
   font-size: 1rem !important;
 }
@@ -292,4 +295,5 @@ code {
   padding: 0 5px 0 5px;
   align-items: center;
   display: inline-flex;
-}
+}
+