#main {  width: 100%; height: 56%; }
 #lunbotu { 
            width:48%; height: 100%; 
            margin: 0 auto;
            border: 1px solid rgb(135,144,191); 
            box-shadow: 0px 0px 20px rgb(231,231,231); 
          }

 #myCarousel { width: 100%; height: 90%; margin: 0 auto;}

 .carousel-inner { width: 100%; height: 100%; }
 .carousel-inner>.item >img { height: 100%;}
 #symbol { width: 100%; height: 10%; margin:0 auto; background: rgb(255,255,255);}
 #symbol  > img { width: 100%;  }

 .carousel-control { width: 12%; height: 20%; border-radius: 100%; 
                     font-size: 10vh; line-height: 100%;
                     position: absolute;
                     top: 36%
                   }
  #pre_btn { left: -14%;}
  #next_btn { right: -14%;}