.水平布置 {
  display: flex;
  flex-direction: row;
}
.垂直布置 {
  display: flex;
  flex-direction: column;
}
.登录框背景 {
  width: 300px;
  background-color: White;
  opacity:1;
  margin-top: 20px;
  border-radius: 20px;
  box-shadow: 0px 0px 10px 3px #a6a6a6;
}