html, body {
  padding: 0;
  margin: 0;
  width: 100%;
  height: 100%;
}

#virtual-controll {
  position: absolute;
  display: none;
  bottom: 6em;
  width: 100%;
  -webkit-user-select: none; /* Safari, Chrome */
  -moz-user-select: none;    /* Firefox */
  -ms-user-select: none;     /* IE 10+ */
  user-select: none;        /* 標準 */
}
#virtual-controll button {
  width: 6em;
  height: 6em;
  padding: 0;
  border-radius: 50%;
  border-color: #00000000;
  -webkit-user-select: none; /* Safari, Chrome */
  -moz-user-select: none;    /* Firefox */
  -ms-user-select: none;     /* IE 10+ */
  user-select: none;        /* 標準 */
}
#virtual-controll button#left, #virtual-controll button#right {
  background-color: rgb(159,159,159);
  margin-left: 2em;
}
#virtual-controll button#jump {
  background-color: rgb(239,220,139);
  margin-left: 4em;
}

@media (max-width: 600px) {
  #virtual-controll {
    display: block;
  }
}