Fix inappropriate CSS rule for Markdown on wiki page (#3766)

public/css/gogs.css

@@ -2162,15 +2162,15 @@ footer .ui.language .menu {
 .repository.wiki.view .ui.sub.header {
   text-transform: none;
 }
-.repository.wiki.view .markdown {
+.repository.wiki.view > .markdown {
   padding: 15px 30px;
 }
-.repository.wiki.view .markdown h1:first-of-type,
-.repository.wiki.view .markdown h2:first-of-type,
-.repository.wiki.view .markdown h3:first-of-type,
-.repository.wiki.view .markdown h4:first-of-type,
-.repository.wiki.view .markdown h5:first-of-type,
-.repository.wiki.view .markdown h6:first-of-type {
+.repository.wiki.view > .markdown h1:first-of-type,
+.repository.wiki.view > .markdown h2:first-of-type,
+.repository.wiki.view > .markdown h3:first-of-type,
+.repository.wiki.view > .markdown h4:first-of-type,
+.repository.wiki.view > .markdown h5:first-of-type,
+.repository.wiki.view > .markdown h6:first-of-type {
   margin-top: 0;
 }
 .repository.settings.collaboration .collaborator.list {

public/less/_repository.less

@@ -1158,7 +1158,7 @@
 			.ui.sub.header {
 				text-transform: none;
 			}
-			.markdown {
+			>.markdown {
 				padding: 15px 30px;
 
 				h1, h2, h3, h4, h5, h6 {