body {
  margin: 0;
  padding: 0;
  font-family: sans-serif;
  background: url(../images/bg.jpg) no-repeat center 0;
  background-size: cover;
  background-position: center 0;
  background-attachment: fixed; /* 仅桌面端生效，移动端在下方媒体查询中关闭 */
}

/* 移动端竖屏：整图横向滑动（桌面端隐藏） */
.pan {
  display: none;
}

@media (orientation: portrait) {
  body {
    background: #000;
    background-attachment: scroll;
  }

  .pan {
    display: flex;
    height: 100vh;
    height: 100svh;
    overflow-x: auto;
    scrollbar-width: none;
  }

  .pan::-webkit-scrollbar {
    display: none;
  }

  .pan img {
    display: block;
    height: 100vh;
    height: 100svh;
    width: auto;
  }
}