Inconsistent space around headings

[michaellenaghan]

I think there's an issue here:

yue.css/src/yue.css

Lines 29 to 30 in 76f4cca

	margin-top: 1.62em;
	margin-bottom: 1em;

Note the progression of top and bottom margins:

.yue h2 {
  ...
  margin-top: 1.42em;
  margin-bottom: 0.4em;
}

.yue h3 {
  ...
  margin-top: 1.62em;
  margin-bottom: 1em;
}

.yue h4,
.yue h5,
.yue h6 {
  ...
  margin-top: 1.4em;
  margin-bottom: 0.8em;
}

h3s margins are larger than both h2s and h4/h5/h6s.