滚动条 默认样式修改 （css）

// html结构
<div class="box">
<div class="boxItem">
<p style="height:300px;">第一级1111</p>
<p style="height:500px;">第一级2222</p>
<p>第一级3333</p>
</div>
</div>

// css 样式
.box{
width: 280px;
height: 600px;
position: absolute;
top: 33px;
left: 13px;
/*cursor: pointer;*/
overflow:hidden;
}
.boxItem{
overflow-x: hidden;
overflow-y: auto;
color: #000;
font-size: 14px;
font-family: "\5FAE\8F6F\96C5\9ED1",Helvetica,"黑体",Arial,Tahoma;
height: 100%;
}
/*滚动条样式*/
.boxItem::-webkit-scrollbar {/*滚动条整体样式*/
width: 4px;     /*高宽分别对应横竖滚动条的尺寸*/
height: 4px;
}
.boxItem::-webkit-scrollbar-thumb {/*滚动条里面小方块*/
border-radius: 5px;
-webkit-box-shadow: inset 0 0 5px rgba(0,0,0,0.2);
background: rgba(0,0,0,0.2);
}
.boxItem::-webkit-scrollbar-track {/*滚动条里面轨道*/
-webkit-box-shadow: inset 0 0 5px rgba(0,0,0,0.2);
border-radius: 0;
background: rgba(0,0,0,0.1);
}