template: distinguish <main> content from <main> wrapper

enkore · web-flow · commit b7e004aced0a · 2022-02-15T18:21:04.000Z
&lt;body&gt;&lt;main&gt;...&lt;/main/&gt;&lt;/body&gt; is added by rst5html.
Seems like the extra main tag was added in some release some time ago,
breaking the layout.
diff --git a/rst_template.txt b/rst_template.txt
@@ -20,7 +20,7 @@
 	</div>
 </header>
 
-<main>
+<main class="content">
 	<!-- document heading -->
 	%(body_pre_docinfo)s
 	<!-- bibliographical data, if any -->
