.big_box {
            position: relative;
            /*width: 1920px;*/
            height: 862px;
            margin: 100px auto;
            /*margin-left: auto;*/
            /* margin-right: auto;*/
             margin-bottom: 0;
            overflow: hidden;
             margin-top: 120px;
        }

        .big_box ul {
            position: absolute;
            left: 0;
            width: 600%;
            /*height: 862px;*/
        }

        .big_box ul li {
            float: left;
        }

        .big_box ul li img {
            width: 100%;
            /*height: 862px;*/
            height: 100%;
    object-fit: scale-down;
        }

        .left {
            position: absolute;
            top: 50%;
            left: 0;
            transform: translateY(-50%);
            background-color: rgba(255, 255, 255, .5);
            width: 30px;
            height: 30px;
            line-height: 30px;
            text-align: center;
        }

        .right {
            position: absolute;
            top: 50%;
            right: 0;
            transform: translateY(-50%);
            background-color: rgba(255, 255, 255, .5);
            width: 30px;
            height: 30px;
            line-height: 30px;
            text-align: center;
        }

        .big_box ol {
            position: absolute;
            bottom: 0;
            /* 这里别给ol限制宽度，让小圆圈的个数自动把ol撑大 */
            left: 50%;
            transform: translateX(-50%);
            height: 10%;
            line-height: 10%;
            text-align: center;
        }

        .big_box ol li {
            float: left;
            width: 20px;
            height: 20px;
            background-color: rgba(0, 0, 0, .5);
            border-radius: 50%;
            margin-left: 5px;
        }

        .big_box ol .current {
            background-color: rgb(251 69 22);
        }

        .left,
        .right,
        ol li {
            cursor: pointer;
        }
        
        .zuo,.you {opacity:0;}
        
   @media (min-width:780px) {
		        .big_box{  margin-top: 120px;}
		    }
		      @media (max-width:768px) {
		        .big_box{  margin-top: 50px;}
		    }
		    
		    @media (max-width:480px){
		   
		         .big_box ol li { width: 10px;
    height: 10px; }
		    }