Integrate Clocker Script in Website

I’ve built a straightforward site in plain HTML, CSS and vanilla JavaScript, and now I want to drop in a “clocker” script so visitors see accurate, live time functionality without page refreshes. I’m not tied to any particular library or plug-in; I simply need a clean, lightweight solution that fits neatly into the existing codebase and works across modern browsers.

Here’s what I expect from you:
• Review my current markup and JS files (roughly 3 pages).
• Add the clocker script, style it so it blends with the site’s minimal design, and comment the code so I can tweak colors or fonts later.
• Give a short note explaining where to place the script tags and how to initialise the clock if I replicate it on another page.

If you think an extra feature such as a countdown or stopwatch is easy to bundle in, let me know—those could be nice add-ons. Otherwise, a clean digital clock display is the priority.

Please send a brief outline of how you’d tackle it, any libraries you’d lean on (if at all), and an estimated turnaround time.