* {
  margin: 0;
  padding: 0;
}

.box {
  width: 270px;
  height: 200px;
  /* border: 2px solid #333; */
  margin: 0px auto;
  position: relative;
  overflow: hidden;
}

.box ul {
  position: absolute;
  list-style: none;
  left: 0;
  top: 0;
}

.box ul li {
  height: 200px;
  float: left;
}

.box ul li img {
  width: 270px;
  height: 200px;
}

    .box ol {
        position: absolute;
        z-index: 9;
        list-style: none;
        height: 10px;
        /*left: 50%;*/
        left: 20%;
        margin-left: -40px;
        bottom: 10px;
    }

.box ol li {
  width: 10px;
  height: 10px;
  border: .5px solid #aaa;
  border-radius: 50%;
  margin-left: 5px;
  float: left;
  background-color: #fff;
  cursor: pointer;
}

.box #btn { display:none;
  position: absolute;
  width: 100%;
  height: 30px;
  top: 50%;
  margin-top: -15px;
  user-select: none;
}

.box .btn {display:none;
  width: 20px;
  height: 30px;
  text-align: center;
  line-height: 15px;
  font-size: 35px;
  z-index: 9;
  background-color: rgba(0, 0, 0, 0.4);
  color: rgb(230, 225, 225);
}

.box .btnLeft {
  float: left;
  margin-left: 0px;
  cursor: pointer;
}

.box .btnRight {
  float: right;
  margin-right: 0px;
  cursor: pointer;
}

.box ol .active {
  background-color: #97c8f8;
}