diff --git a/packages/nav-bar/index.less b/packages/nav-bar/index.less
index 13720184..627373c7 100644
--- a/packages/nav-bar/index.less
+++ b/packages/nav-bar/index.less
@@ -7,6 +7,7 @@
   height: var(--nav-bar-height, @nav-bar-height);
   line-height: var(--nav-bar-height, @nav-bar-height);
   background-color: var(--nav-bar-background-color, @nav-bar-background-color);
+  box-sizing: content-box;
 
   &__content {
     position: relative;