I have been given a design with a number of variable height items stacked vertically in a fixed height container, with a variable width. So the idea is that the items can scroll off screen (will be in a wrapper) so that they can be scrolled horizontally onto screen.
I’m having trouble coming up with a solid way of organising the divs so that they stack reliably. Here is what I’m trying to achieve.

Try this – DEMO
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CSS