CSS in textbox hover - chrome only issue

-- HikaShop version -- : 2.3.4
-- Joomla version -- : 3.3.6

Hi Hikashop
im having trouble with an input textbox resizing when hovered - only in chrome
174.132.121.226/~richardt/index.php/hika...r-categories-listing

its dimensions are 280 by 24
but when hovered it grows to 280 by 38

only in Chrome - can you suggest a fix please?

thanks