There are a couple of ways you can approach that. One would be to use some CSS to apply a min-height to the #home-midde .widget that is equal to the height of the tallest widget. That would cause the shorter widgets to grow so they are the height that you set for the tallest one. The advantage of using a min-height instead of a height is if the content changes in the widget and it needs to be taller than the min-height, it can stretch. If a height is set it won’t allow it to stretch.
and right above that add this:
(See support post for code)
That’s adapted from another theme of mine and not from Bottega so I can’t promise it won’t run into any quirks, but it might work out well.