We require a countdown script, which works as follows:
A user enters a date and time into a form or passes it in the URL. The script would then show a countdown (dd days, hh:mm:ss). For the last 30 seconds, this countdown would be replaced in such a way that only the remaining seconds are shown in large digits in the center of the page. When the countdown reaches 0, a firework should be shown, preferably with sound effects.