Steps to Reproduce

iOS only (confirmed in 14.3)
http://zkfiddle.org/sample/2grsqn3/1-Navbar-submenu-wrong-position
Scroll the page first and click "Get Started" or "Contact".

Current Result

The submenu appears in the wrong position.

Expected Result

The submenu appears right below the navbar.

Debug Information

ZK >= 9.0.0 (9.1.0 not included)
The previous version (ZK 9.5.1) test was passed.
Not sure if the root cause is the Safari version or not.

Workaround