style.css

body {
  font: 14px "Lucida Grande", Helvetica, Arial, sans-serif;
}

:root {
  --speed-value: 10%;
}

#canvas_holder {
  margin-bottom: 30px;
}

#input_holder {
  width: 500px;
  height: 28px;
  position:relative;
  white-space: nowrap;
  overflow: hidden;
}

#disk_count_holder {
  top: 2px;
  left: 0;
  position: absolute;
}

#disk_count {
  width: 40px;
  height: 20px;
}

#move_to_holder {
  top: 0;
  right:0; 
  position:absolute;
}

#move_to {
  width: 100px;
  height: 28px;
}

#button_holder {
  width: 500px;
  display: inline-flex;
  overflow: hidden;
  margin: 30px 0;
}

button {
  width: 100px;
  height: 30px;
  cursor: pointer;
  margin-left: 100px;
}

button:disabled {
  cursor: default;
}

input[type=range] {
  -webkit-appearance: none;
  -moz-appearance: none;
  width: 500px;
  height: 6px;
  border-radius: 3px;
  border: 1px solid black;
  outline: none;
  background: #58f;
  margin: 16px 0 16px 0;
  background: linear-gradient(to right, #25c 0%, #25c var(--speed-value), #ddd var(--speed-value), #ddd 100%);
}

input[type=range]::-webkit-slider-thumb {
  -webkit-appearance: none;
  -moz-appearance: none;
  width: 12px;
  height: 24px;
  border-radius: 20%;
  border: 1px solid black;
  cursor: pointer;
  background: #25c;
}

input[type=range]::-moz-range-thumb {
  -webkit-appearance: none;
  -moz-appearance: none;
  width: 11px;
  height: 23px;
  border-radius: 20%;
  border: 1px solid black;
  cursor: pointer;
  background: #25c;
}

input[type=range]:focus::-webkit-slider-runnable-track {
  -webkit-appearance: none;
  -moz-appearance: none;
  outline: 1px dotted #333;
  outline-offset: 6px;
}

input[type=range]:focus::-moz-range-track {
  -webkit-appearance: none;
  -moz-appearance: none;
  outline: 1px dotted #333;
  outline-offset: 16px;
}