fix styles for label and h3

merged from <92e13faeb8>

Signed-off-by: WaitSpring <me@waitspring.com>

resources/mixins.less

@@ -72,14 +72,25 @@
 		list-style: none;
 	}
 
+	label,
 	h3 {
 		padding-bottom: 0.15em;
 		margin: 0.25em 0 0.75em 0;
 		font-family: @fonts-serif;
+		display: block;
+	}
+
+	label {
+		font-size: 1em;
+		font-weight: normal;
+	}
+
+	h3 {
 		font-size: 1.125em;
 		font-weight: bold;
 	}
 
+	.mw-portlet > div,
 	.mw-portlet-body {
 		margin-bottom: 2em;
 	}