/* 返回顶部按钮样式 */
.back-to-top {
  position: fixed;
  right: 20px;
  bottom: calc(50% + 100px); /* 根据底部横幅高度调整 */
  transform: translateY(50%);
  width: 40px;
  height: 40px;
  background: #ff0000; /* 红色背景 */
  color: white;
  text-align: center;
  line-height: 40px;
  border-radius: 50%;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.3s;
  z-index: 9999;
  box-shadow: 0 0 5px rgba(0, 0, 0, 0.3);
}
.back-to-top.show {
  opacity: 1;
}