<!DOCTYPE html>
<html>
  <head>
    <style>
input {
  width: 10px;
  height: 1.5em;
  outline: 1px dotted black;
  color: white;
  background: white;
  /* Disable baseline alignment, so that our y-position isn't influenced by the
   * choice of font inside of input: */
  vertical-align: top;
}
    </style>
  </head>
  <body>
    <input type="time">
  </body>
</html>