Switch to side-by-side view

--- a/website/perfs.html
+++ b/website/perfs.html
@@ -30,7 +30,7 @@
 
     <div class="content">
 
-      <h1 class="intro">Recoll: Indexing performance and index sizes</h1>
+      <h1>Recoll: Indexing performance and index sizes</h1>
 
       <p>The time needed to index a given set of documents, and the
 	resulting index size depend of many factors, such as file size