diff --git a/css/area_nav-metabox.less b/css/area_nav-metabox.less
index 4084ac8..8aba8a3 100755
--- a/css/area_nav-metabox.less
+++ b/css/area_nav-metabox.less
@@ -57,6 +57,7 @@
                 display: block;
                 background-color: @color-site-bg;
                 border: 1px solid @color-border-light;
+                border-bottom-color: @color-site-bg;
                 border-radius: @fix_border-radius @fix_border-radius 0 0;
                 color: @color-nav;
                 font-size: @font-size-small;