Apply suggestions from code review

Co-authored-by: Richard Schreiber <schreiber@rami.io>

src/pretix/static/pretixcontrol/js/ui/dragndroplist.js

@@ -3,7 +3,7 @@ $(function () {
     $("[data-dnd-url]").each(function(){
         const container = $(this),
             url = container.data("dnd-url"),
-            handle = $('<span class="btn btn-default btn-sm dnd-sort-handle"><i class="fa fa-arrows"></i></span>');
+            handle = $('<button type="button" class="btn btn-default btn-sm dnd-sort-handle"><i class="fa fa-arrows"></i></button>');
 
         container.find(".dnd-container").append(handle);
         container.find(".sortable-up, .sortable-down").addClass("sr-only");

src/pretix/static/pretixcontrol/scss/main.scss

@@ -852,7 +852,8 @@ tbody[data-dnd-url] {
 .sortable-sorting tbody:not(.sortable-dragarea) {
     opacity: .4;
 }
-th span.not-bold {
+.font-normal {
+    font-style: normal;
     font-weight: normal;
 }
 tbody th {