fix (#2182): use @nav-header-height variable

use @nav-header-height

src/components/SiderMenu/index.less

@@ -63,8 +63,8 @@
 
 :global {
   .top-nav-menu li.ant-menu-item {
-    height: 64px;
-    line-height: 64px;
+    height: @nav-header-height;
+    line-height: @nav-header-height;
   }
   .drawer .drawer-content {
     background: #001529;