如何使用纯CSS绘制微调器？

<div class="slider"></div>

.slider {
  width: 200px;
  height: 20px;
  background-color: #ccc;
  position: relative;
  border-radius: 10px;
}

.slider::before {
  content: "";
  width: 20px;
  height: 20px;
  background-color: #fff;
  position: absolute;
  top: -5px;
  left: 0;
  border-radius: 50%;
  box-shadow: 0 0 5px rgba(0, 0, 0, 0.3);
}

.slider::after {
  content: "";
  width: 20px;
  height: 20px;
  background-color: #fff;
  position: absolute;
  top: -5px;
  right: 0;
  border-radius: 50%;
  box-shadow: 0 0 5px rgba(0, 0, 0, 0.3);
}

.slider:hover {
  background-color: #ddd;
}

.slider:hover::before,
.slider:hover::after {
  background-color: #aaa;
}

.slider:active::before,
.slider:active::after {
  background-color: #888;
}