Merging extents to get fewer extents (defragmentation) is beneficial to customers who have a large number of extents in a partition and are likely to run into the partition page overflow problem.

A similar strategy is used to prevent the dreaded stack overflow, which occurs when navigating away from a page returns flow to a page that was previously traversed.

So when you scroll the page to show the invisible part, the DIV is not big enough, causing the text to overflow.