Weird Product Display when turned on bootstrap

-- url of the page with the problem -- : www.vivatec.hk
-- HikaShop version -- : Latest Essential Edition
-- Joomla version -- : x2.5
-- Error-message(debug-mod must be tuned on) -- :

Once turned on the "use bootstrap design" on my site, the products display is not regularly 4 items a row, may I know why and how to fix it? Thousands Thanks

Hi,

You have to give a fixed height to the div containing the product. Something like this should do the job: