.dialog {
  position: fixed; left: 0; top: 0;
  width: 100%; height: 100%;
  z-index: 9999;
  opacity: 0; visibility: hidden;
  transition: .3s;
}
.dialog.is-show { opacity: 1; visibility: visible; }
.dialog-inner {
  position: absolute; left: 50%; top: 50%;
  transform: translate(-50%, -50%);
  padding: 12px 24px;
  background-color: #fff;
  z-index: 2;
}
.dialog-background {
  position: absolute; left: 0; top: 0;
  width: 100%; height: 100%;
  background-color: rgba(0,0,0,.8);
  z-index: 1;
}