bug(4937)

src/css/knowledgeMap.less

@@ -96,7 +96,7 @@
                     background: #fff;
                     color: #333;
                     border: 1px solid #e6e6e6;
-                    z-index: 2;
+                    z-index: 3;
                 }
                 .selectItem:hover{
                     background: #E2ECFF;

src/css/knowledgeTree.less

@@ -99,7 +99,7 @@
                     background: #fff;
                     color: #333;
                     border: 1px solid #e6e6e6;
-                    z-index: 2;
+                    z-index: 3;
                 }
                 .selectItem:hover{
                     background: #E2ECFF;