body, button, h1{
  padding: 0;
  margin: 0;
}

body {
  background-color: #aaa;
}

header {
  padding: 0;
  padding-left: 0.8em;
  background-color: #3f3f3f;
  border-bottom: 1px solid #454545;
  color: #fff;
}

header h1 {
  line-height: 2em;
  font-size: 1.3em;
}

#time {
  width: 100%;
  text-align: center;
  font-size: 3em;
  margin-top: 0.3em;
}

#kei {
  display: block;
  margin: 0 auto;
}

#buttons {
  width: 100%;
  position: absolute;
  bottom: 0;
}

#start_button {
  width: 100%;
}

#restart_button, #stop_button {
  width: 50%;
  display: none;
  float: left;
}

#reset_button {
  width: 50%;
  display: none;
  float: right;
}
