.banner_bg::before {
  position: absolute;
  top: auto;
  right: auto;
  bottom: 0;
  left: 0;
  z-index: 2;
  content: "";
  width: 100%;
  height: 40%;
  background: linear-gradient(0deg, rgba(0, 0, 0, 0.6), transparent);}
/*样式*/
.focus_bg .slick-slide img {
  
    width: 100%;
    height: 100%;} 

.focus_bg .slick-slide img {
    width: 100%;
    max-height: 299px;
    height: 100%;
    object-fit: cover;}