In this html, a ball will drop on a pile of squares.
The ball's Density: 1
The Square's Density: 100
We can see the pile collapses in about 10 seconds.
if the squares' density are lower, it collapses sooner like all the squares become mad.
However, you can open the capx below, run it's layout;
it won't ever collapse in capx.
So if you made something like the buildings in "Angry Bird",
you'd think you did a great job in capx's layout running,
and found all the buildings collapsed in exported html because of a tiny touch.