http://forwhoallvglhpsx6dhycfb4fu4a2lqkvxtwlivruw765qxofyns7wqd.onion/stopwatch.php
That number is seen on the top left. Javascript increments the time and displays the time in the center. When JS isn't there, PHP shows a static time value, which will be refreshed automatically. (That refresh also calibrates the JS in case of PC sleep.)