Edit color and add sound

Sound do not play because there is a security on Chrome. User need to interact with the page.

js/main.js

@@ -1,5 +1,7 @@
 /* HTML contents */
+var body = document.body;
 var timerHTML = document.getElementById("timer");
+var ding = document.getElementById("ding");
 
 /* GET url variable */
 const queryString = window.location.search;
@@ -14,6 +16,8 @@ let localTimer = setInterval(() => {
     timer.decrement();
     if(timer.getTime() < 0) {
         clearInterval(localTimer);
-        timerHTML.style.color = "red";
+        body.style.backgroundColor = "red";
+        timerHTML.style.color = "white";
+        ding.play();
     }
 }, 1000);