Steps to Reproduce

run the attachment
(optional: choosing atlantic theme makes it more obvious)
all themes are affected

Current Result

Expected Result

consistent markup/styling - same as in window component

Debug Info

this seems like an issue with the panel mold where the close button is rendered as a button, while all other window/panel buttons are rendered as div elements
hence the styles don't match giving inconsistent results

Root Cause

https://github.com/zkoss/zk/blob/v8.0.5/zul/src/archive/web/js/zul/wnd/mold/panel.js#L29
renders a <button>, while the other buttons are rendered as <div>