.hide {
  display: none;
}

body, ul, p {
  margin: 0;
  padding: 0;
}

body {
  font-size: 14px;
  line-height: 1.5;
  background: #f2f2f2;
}

.wrapper {
  position: relative;
  height: 300px;
  width: 600px;
  margin: 40px auto;
  overflow: hidden;
  background: skyblue;
}

.content {
  height: 100%;
  overflow-y: auto;
}

.scrollBar {
  position: absolute;
  top: 0;
  right: 0;
  width: 12px;
  height: 100%;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
}

.scrollBar .barTop, .scrollBar .barBottom {
  position: absolute;
  width: 12px;
  height: 12px;
  text-align: center;
  background: #fff;
  cursor: pointer;
}

.scrollBar .barTop {
  top: 0px;
}

.scrollBar .barBottom {
  bottom: 0px;
}

.scrollBar .barMiddle {
  position: absolute;
  width: 12px;
  top: 12px;
  bottom: 12px;
  background: #000;
}

.scrollBar .barMiddle .bar {
  position: absolute;
  top: 0px;
  left: 0px;
  right: 0px;
  width: 8px;
  margin: auto;
  background: skyblue;
  border-width: 2px;
  border-style: solid;
  border-color: inherit;
  border-top: none;
  border-bottom: none;
  border-radius: 5px;
}

.desc {
  color: #333;
  width: 578px;
  padding: 10px;
  margin: 0 auto;
  line-height: 2;
  border: 1px dashed #333;
}