styles: Use base line-height on all elements (wikimedia#408)

We're using 1.6 as base line height on Vector and MinervaNeue is not
setting it at all, therefore exceeding. It's preferable to rely on
standard typographic rule of thumb and in production values.

css/build/wmui-style-guide.css

@@ -1,6 +1,6 @@
 /* ::: Vendor Imports ::: */
 /* Load files from 'node_modules' folders with postCSS-import plugin.
- * Modules specified in package.json file */
+ * Modules specified in package.json file. */
 /**
  * WikimediaUI Base v0.17.0
  * Wikimedia Foundation user interface base variables
@@ -504,7 +504,7 @@ template {
 }
 */
 :root {
-	/* HACK; Add Georgia to serif fallback as long as WikimediaUI Base isn't updated */ /* stylelint-disable-line value-keyword-case */
+	/* HACK; Add Georgia to serif fallback as long as WikimediaUI Base isn't updated. */ /* stylelint-disable-line value-keyword-case */
 	/* Setting bold to `600` as our stack works better with it, only Lato is on the edge.
 	   Helvetica and Arial fallback gracefully to `700`, see T246791. */
 }
@@ -580,7 +580,6 @@ blockquote {
 	font-family: Georgia, serif; /* Fallback */
 	font-size: 2rem;
 	font-style: italic;
-	line-height: 1.5;
 }
 blockquote cite {
 	display: block;
@@ -606,7 +605,6 @@ hr {
 }
 p {
 	margin: 3.2rem 0 0;
-	line-height: 1.5;
 }
 h1 + p,
 	h2 + p,