fix margin around descriptions in description list

* apply margin to top of subsequent terms (using dd + dt selector) instead of end of description
* add margin top to principal text

Author: mojavelinux

preview-src/index.adoc

@@ -192,6 +192,7 @@ sed::
 splendide sed
 
 mea::
+tad::
 agam graeci
 
 Let's look at that another way.

src/css/doc.css

@@ -948,11 +948,12 @@
 }
 
 .doc .dlist dd {
-  margin: 0 0 0.25rem 1.5rem;
+  margin: 0 0 0 1.5rem;
 }
 
-.doc .dlist dd:last-of-type {
-  margin-bottom: 0;
+.doc .dlist dd + dt,
+.doc .dlist dd > p:first-child {
+  margin-top: 0.5rem;
 }
 
 .doc td.hdlist1,