.bj {
  width: 100%;
  min-height: 100vh;
  overflow: hidden;
  /* background-size: auto 100%; */
}
.top {
  position: relative;
  text-align: center;
  /* margin-top: 50px; */
}
.kxcLogo {
  position: absolute;
  left: 0;
}
.top>img{
  margin-top: 20px;
}
.main {
  background: url(/kxc/kxc_EjBj.png)no-repeat center;
  background-size: 100% 100%;
  overflow: hidden;
  padding: 15px;
  margin-top: 50px;
}
.main li {
  float: left;
  width: calc(25% - 10px);
  text-align: center;
  padding: 0 5px;
}
.main li a {
  display: block;
}
.main li img{
  width: 100%;
  /* filter: contrast(50%); */
  /* filter: grayscale(50%); */
  transition: all 0.3s;
}
.main li img:hover{
  box-shadow: 0 4px 8px 0 rgb(0 0 0 / 20%), 0 6px 20px 0 rgb(0 0 0 / 19%);
  /* filter: grayscale(0); */
}

/* 数说科学城 */
.SS {
  background: url(/kxc/sskxc_Bj.png)no-repeat top center;
}
/* 图说科学城 */
.TS {
  background: url(/kxc/tskxc_Bj.png)no-repeat top center;
}
@media screen and (min-width: 1199px){
  .main li img:hover{
    transform: translate(0 , -10px);
  }
    .gy:hover{
    content: url(/kxc/tskxc1.png);
  }
  .xx:hover{
    content: url(/kxc/tskxc2.png);
  }
  .cg:hover{
    content: url(/kxc/tskxc3.png);
  }
  .qy:hover{
    content: url(/kxc/tskxc4.png);
  }
}
@media screen and (max-width: 1200px){
  .top>img{
    width: 80%;
  }
  .main li {
    width: calc(50% - 10px);
  }
  .kxcLogo{
    display: none;
  }
}