[ivette] Changing pivot table font and removing a drag detail

ivette/src/frama-c/kernel/PivotTable-style.css

 .pvtUi {
     color: var(--text);
-    font-family: Verdana;
     border-collapse: collapse;
 }
 .pvtUi select {
@@ -21,7 +20,6 @@ table.pvtTable {
     border-collapse: collapse;
     margin-top: 3px;
     margin-left: 3px;
-    font-family: Verdana;
 }
 table.pvtTable thead tr th,
 table.pvtTable tbody tr th {
@@ -141,7 +139,7 @@ table.pvtTable tbody tr td {
 }
 
 .pvtAxisContainer li {
-    padding: 8px 6px;
+    margin: 8px 6px;
     list-style-type: none;
     cursor: move;
 }