Enable smooth scrolling for anchors

Author: Claudio Cortese

_includes/css/agency.css

@@ -4,6 +4,10 @@
  * For details, see http://www.apache.org/licenses/LICENSE-2.0.
  */
 
+html {
+    scroll-behavior: smooth;
+}
+
 body {
     overflow-x: hidden;
     font-family: "Chakra Petch", sans-serif;