<style>body{background:#111;color:#fff;user-select:none;text-align:center}*{font-size:28}input{margin:9}</style>
<input type=number style=width:79;text-align:right min=0 value=2 id=M>m
<input type=number style=width:79;text-align:right min=0 value=0 id=S>s<br>
<input id=N style=width:199 placeholder=Reminder>
<button id=A onmousedown=setInterval(U,1e3,A.disabled=M.disabled=S.disabled=P=1) style=width:99>Start</button><script>

// globals
// M = minutes
// S = seconds
// N = notification
// A = sta