new style for code blocks

Author: gsmolk

pg_probackup/stylesheet.css

@@ -394,9 +394,15 @@ table.CAUTION,
 	margin-left: 40px;
 }
 
-
 .book .sidebar {
     padding: 8px;
     background: #FFF;
     width: auto;
 }
+
+.book pre {
+    background: #f5f5f5;
+    padding: 10px;
+    border: 1px solid #ccc;
+    border-radius: 4px;
+}