*{ margin:0;padding:0;-webkit-tap-highlight-color: rgba(0,0,0,0);-moz-user-select:none;font-family: Microsoft Yahei;}
.top {
  position: absolute;
  top: 0;
}

.right {
  position: absolute;
  top: 0;
  bottom: 0;
  right: 0;
  margin: auto;
}

.left {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  margin: auto;
}

.bottom {
  position: absolute;
  bottom: 0;
}

.center {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  margin: auto;
}