update header shadow

src/layouts/BasicLayout.less

@@ -3,7 +3,7 @@
 .header {
   padding: 0 12px 0 0;
   background: #fff;
-  box-shadow: 0 1px 4px rgba(0, 21, 41, .12);
+  box-shadow: 0 1px 4px rgba(0, 21, 41, .08);
   position: relative;
 }