Update default.html

docs/_layouts/default.html

@@ -18,7 +18,7 @@
         <div class="row">
             {% include nav.html %}
             <main id="markdown-content" class="col-12 col-md-8 px-2 markdown-body">
-	    	<div class="ms-MessageBar ms-MessageBar--error">
+	    	<div class="ms-MessageBar ms-MessageBar--error ms-MessageBar-singleline">
 		  <div class="ms-MessageBar-content">
 		    <div class="ms-MessageBar-icon">
 		      <i class="ms-Icon ms-Icon--ErrorBadge"></i>