.banner{background:url(imgs/top1.jpg) no-repeat center;background-size:cover;position:relative;height:30vw;font-size:1.5rem}
@media(min-width:768px){
.banner{height:16vw;font-size:4rem}
}
.banner:before{content:'';position:absolute;width:100%;height:100%;top:0;left:0;opacity:.1;background:#000;z-index:1}
.banner1 {
    background: url(imgs/space1.jpg);
  }