adapt.css: add blue highlight for active menuitem

adapt.css

@@ -105,12 +105,14 @@ appears on the left side of the page.
 #menu a {
   color: #222;
   border: none;
-  padding: 0.6em 0 0.3em 0.6em;
+  padding: 0.6em 0 0.3em 0.4em;
+  border-left: 5px solid transparent;
   font-size:85%;
 }
 #menu a.selflink {
   background-color: #e1e1e1;
   border-top: 1px solid #b7bac3;
+  border-left: 5px solid #3a6daf;
   font-weight: bold;
 }
 #menu a:hover,