add api for descriptor to root domain, tidying things up

files/web/html/src/styles.css

@@ -49,3 +49,15 @@ li {
 #host_metrics_table tbody tr td :nth-of-type(even) {
      background-color: #3e5c78;  
 }
+
+.help-link{
+    cursor:pointer;
+    user-select:none;
+    color: #2c3e50;
+    text-align: right;
+}
+.help-link:hover{ text-decoration:underline; }
+
+#helpText{
+    display:none;               /* hidden by default */
+}