diff --git a/Doc/tools/sphinxext/static/basic.css b/Doc/tools/sphinxext/static/basic.css
--- a/Doc/tools/sphinxext/static/basic.css
+++ b/Doc/tools/sphinxext/static/basic.css
@@ -39,6 +39,7 @@
 
 div.sphinxsidebarwrapper {
     padding: 10px 5px 0 10px;
+    word-wrap: break-word;
 }
 
 div.sphinxsidebar {