This is a digital stopwatch built with HTML, CSS, and vanilla JavaScript.

It originally used setInterval but was later improved with performance.now() for more accurate time tracking.

Rather than incrementing blindly, it calculates the actual elapsed time at each update, ensuring precision even with lag.

The UI is fully responsive and works on both desktop and mobile.

To address mobile 100vh issues, it uses a JavaScript workaround that sets a CSS variable based on the real viewport height.

The stopwatch includes Play, Pause, and Reset features, and updates every 10 milliseconds for centisecond-level accuracy.