Slik Slider-创建`center`滑块

Question

我想使用Slik Slider创建一个中心滑块。但是使用Slik Slider我遇到了一个问题，它不能正常工作。实际上，中间的项目并未突出显示。我的代码和JSFiddle如下所示。我怎么才能修复它呢？

HTML：

<div id=costumers>
      <div id="listSlider-right-icon">
            <i id="listSlider-right-arrow" class="fa fa-2x fa-square color-green">
                <i class="play-icon fa fa-play color-white"></i>
            </i>
        </div>
      <div id="listSlider">
            <div class="costumers_box">
              <h3>
              1
              </h3>
            </div>
            <div class="costumers_box">
              <h3>
              2
              </h3>
            </div>

            <div class="costumers_box">
              <h3>
              3
              </h3>
            </div>
            <div class="costumers_box">
              <h3>
              4
              </h3>
            </div>
            <div class="costumers_box">
              <h3>
              5
              </h3>
            </div>
            <div class="costumers_box">
              <h3>
              6
              </h3>
            </div>
            <div class="costumers_box">
              <h3>
              7
              </h3>
            </div>
            <div class="costumers_box">
              <h3>
              8
              </h3>
            </div>
        </div>
        <div id="listSlider-left-icon">
            <i id="listSlider-left-arrow" class="fa fa-2x fa-square color-green">
                <i class="play-icon fa fa-play color-white"></i>
            </i>
        </div>
      </div>

CSS：

#listSlider{
    display: flex;
    justify-content: space-around;
    width: 70%;
    margin-top: 110px;
}
.costumers_box{
    background-color: #333333;
    width: 160px;
    height: 110px;
    border-radius: 5px;
    margin-left: 10px;
    display: flex;
    justify-content: center;
    align-items: center;
}
.costumers_box h3{
    color: white;
}
#costumers{
    width: 100%;
    height: 250px;
    background-color: #383838;
    margin-bottom: 30px;
    position: relative;
    display: flex;
    justify-content: center;
}
#listSlider-left-icon, #listSlider-right-icon{
    position: absolute;
    margin-top: 150px;
    cursor: pointer;
}
#listSlider-right-icon{
    right: 10%;
}
#listSlider-left-icon{
    left: 10%;
}

#listSlider-left-arrow i, #listSlider-right-arrow i{
    font-size: 12px;
    position: absolute;
    left: 50%;
    top: 0.6em;
    margin-left: -7px;
}
#listSlider-left-arrow i{
     transform: rotate(180deg);
}
#listSlider-right-arrow i{
    margin-left: -5px;
    top: 0.7em;
}
.color-white{
    color: white;
}
.color-green{
    color: #01a89e;
}

这是我的JSFiddle