Joe Workman’s product page states that you will use Jack “all the time, over and over again – shadows, transparency, borders, background images…” – there are a couple of stacks on the market that will allow some of Jack’s functions, but none that even come close to allowing all of them. Jack doesn’t stop at shadows, borders and backgrounds…One of Jack’s most useful features IMHO is the flexibility when defining the height of the stack –Automatically to fit the content; to a Static size set in pixels; to a Flexible size as a percentage of the browser window or the parent frame; Proportionally – 16:9, 4:3 or any size you care to enter, or – when using the Foundation theme – Equalised. Maximum and Minimum Sizes – both height and width – can be set to pixels, percent, r-em (Root Font Size) or em (Font Size).Vertical scrolling can be activated within Jack, so that e.g. a group of images or icons can be scrolled across the screen like a slide-show. Horizontal scrolling of content overflow goes without saying.