Hide versions in reference when versions dictionary not available (#16719)

Resolve #16716

Author: Kordyjan

scaladoc-js/main/src/versions-dropdown/DropdownHandler.scala

@@ -31,6 +31,7 @@ class DropdownHandler:
   private def disableButton() =
     val btn = document.getElementById("dropdown-trigger").asInstanceOf[html.Span]
     btn.classList.add("disabled")
+    btn.classList.add("hidden")
 
   private def getURLContent(url: String): Future[String] = Ajax.get(url).map(_.responseText)
 

scaladoc/resources/dotty_res/styles/theme/layout/header.css

@@ -41,6 +41,10 @@
   margin-right: calc(2 * var(--base-spacing));
 }
 
+.header-container-left span.hidden {
+  display: none;
+}
+
 .header-container-right {
   display: flex;
   align-items: center;