Steps to Reproduce

run the attached example accordion-animation-jumpy.zul

Current Result

when switching tabs the tabs below jump during the animation

Expected Result

stable positions during animations similar to the workaround accordion-animation-workaround.zul

Debug Info

paddings/borders of the .z-tabbox-content element are not animated causing the jumpy positions
(related to box-size: border box)

Root Cause

the slideUp/slideDown functions don't account for padding and borders
https://www.zkoss.org/javadoc/latest/jsdoc/_global_/jqzk.html#slideDown(zk.Widget,%20_global_.Map)

Workaround

move border/paddings into a separate <div> element and adjust CSS styles
see: accordion-animation-workaround.zul