fix:bug header style (#5904)

src/components/GlobalHeader/index.less

@@ -13,7 +13,7 @@
 
 .right {
   float: right;
-  height: 100%;
+  height: @layout-header-height;
   margin-left: auto;
   overflow: hidden;
   .action {
@@ -51,7 +51,6 @@
 }
 
 .dark {
-  height: @layout-header-height;
   .action {
     color: rgba(255, 255, 255, 0.85);
     > i {