Editor: Heading before paragraph spacing is the same

What's the problem?

The before paragraph spacing (negative space above the heading) is virtually the same for all four headings, which does not make sense in a lot of layouts. See screenshot.

What's expected?

H3 and H4 especially need to have a reduced spacing so that there isn't so much space between blocks, but we should adjust them all so that H1 to H4 all progressively have less space. This will help with establishing better visual hierarchy across pages.