.box {
  width: 100px;
  height: 100px;
  line-height: 100px;
  text-align: center;
  background-color: #00aa9d;
}
/* 中心点 */
.center {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  border: 2px solid;
}

.container {
  position: relative;
  margin: 0 auto;
  width: 100px;
  height: 200px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: transform 2s;
}

.container:hover {
  /* 沿着x轴旋转180° */
  transform: rotateZ(180deg);
}

/* 初始化 */
body {
  width: 100vw;
  height: 100vh;
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  align-items: center;
}