body{font-family:Arial,sans-serif;max-width:1200px;margin:auto;padding:20px}
.track{height:60px;border:1px solid #999;position:relative;margin-bottom:20px}
.walker{width:16px;height:16px;border-radius:50%;position:absolute;top:22px}
canvas{border:1px solid #999;width:100%;max-width:1000px}