```html
body {
fontfamily: Arial, sansserif;
textalign: center;
backgroundcolor: f0f0f0;
}
clock {
fontsize: 48px;
margintop: 100px;
color: 333;
}
function updateClock() {
var now = new Date();
var hours = now.getHours();
var minutes = now.getMinutes();
var seconds = now.getSeconds();
// Add leading zeros if necessary
hours = (hours < 10 ? "0" : "") hours;
minutes = (minutes < 10 ? "0" : "") minutes;
seconds = (seconds < 10 ? "0" : "") seconds;
// Format the time as HH:MM:SS
var timeString = hours ":" minutes ":" seconds;
// Update the clock's display
document.getElementById("clock").innerText = timeString;
}
// Update the clock every second
setInterval(updateClock, 1000);
// Initial call to display the clock immediately
updateClock();