#backToTopBtn {
      display: none;
      position: fixed;
      bottom: 20px;
      right: 20px;
      z-index: 99;
      font-size: 16px;
      cursor: pointer;
      padding: 10px;
      border-radius: 4px;
      background-color: #555;
      color: #fff;
      border: none;
  }

  #backToTopBtn:hover {
      background-color: #777;
  }

  #myCarousel {
    width: 100%;
    height: 100vh; /* 使用视口高度作为高度，使其铺满整个屏幕 */
  }
  
  .carousel-inner {
    width: 100%;
    height: 100%;
  }
  
  .carousel-inner .item {
    width: 100%;
    height: 100%;
  }
  
  .carousel-inner .item img {
    object-fit: cover; /* 使用cover来填充并裁剪图像，以适应容器大小 */
    width: 100%;
    height: 100%;
  }

  .layer {
    width: 100%;
    height: 100%;
    position: fixed;
    top: 0;
    left: 0;
    filter: alpha(opacity=50);
    opacity: .5;
    background: #000;
    z-index: 1000;
    display: none
  }
  
  .left-align {
    text-align: left;
}