* add .nav-default style.

src/less/components/navs.less

 /// ========================================================================
 /// Bootstrap: navs.less
 /// https://github.com/twbs/bootstrap/blob/master/less/navs.less
-/// 
+///
 /// ZUI: The file has been changed in ZUI. It will not keep update with the
 /// Bootsrap version in the future.
 /// http://zui.sexy
@@ -74,6 +74,19 @@
 }
 
 
+// Default simple nav
+
+.nav-default {
+  > li {
+    float: left;
+
+    > a {
+      border-radius: @border-radius-base;
+    }
+  }
+}
+
+
 // Pills
 
 .nav-pills {