Custom theme Navigation panel showing diff in IE8 and Mozilla/Chrome

Dear All,

in Portal 7.3 Recently AJAX Portal standard theme modified as per our requirement (Red Navigation panel) and fallowed steps with help of below document.

How to customize your Ajax Framework page with SAP NetWeaver Portal 7.30

Everything is working fine in IE8 but when we open the same in Mozilla or Google chrome  it's showing navigation panel scroll bar gap.

if anyone help on this really helpful and appreciated.

IE 8 as showing below (here there is no issue)

But other Browsers like Mozilla/Charome showing scroll bar gap.

Thanks

Nageswara