A vertical scroll bar and the three factors of the scroll bar style modified

A vertical scroll bar and the three factors of the scroll bar style modified

Explain the
hidden-ovflow-box is generated scroll bar area

.teacherstudent-page .hidden-ovflow-box{
height: calc(100% - 179px);
overflow: hidden;
overflow-y: auto;
}

It produces three essential elements of the scroll bar

Precautions == "If you no scroll bar, move the scroll bar area give you set a fixed height.
For example, a fixed height is 1000px; if produced a scroll bar.
Description is height: calc (100% - 179px ); this a problem.
Today I met. At this point you go step by step to check hidden-ovflow-box of the parent element is set high 100%

Another point
height: calc (100% - 179px ); this dynamically calculated height must be accurate.
Whether the person with the next element of the same level will be problems.
The question is: scroll bar area inside the element level higher than the scroll bar elements outside the region.

html

 <div class="hidden-ovflow-box">
                    <div
                        :class="{infolistmoduleactive:currentIndex==index}"
                        class="info-list-module"
                        @click="handlerCurrentPerson(index,item)"
                        v-for="(item,index) in leftListData"
                        :key="index"
                    >   
                    </div>
 </div>

css

.teacherstudent-page .hidden-ovflow-box{
    height: calc(100% - 179px);
    overflow: hidden;
    overflow-y: auto;
}
/* 滚动条样式开始 */
.teacherstudent-page .hidden-ovflow-box::-webkit-scrollbar {
  /*滚动条整体样式*/
  width: 10px; /*修改滚动条的宽度*/
  /*高宽分别对应横竖滚动条的尺寸*/
  height: 4px;
}

.teacherstudent-page  .hidden-ovflow-box::-webkit-scrollbar-thumb {
  /*滚动条里面小方块*/
  border-radius: 5px;
  background: #cccccc;
}

.teacherstudent-page  .hidden-ovflow-box::-webkit-scrollbar-track {
  /*滚动条里面轨道*/
  border-radius: 0;
  background: #e5e7ef;
}