Modify the default scroll bar style

.inner{
            width: 265px;
            height: 400px;
            position: absolute;
            top: 33px;
            left: 13px;
            /*cursor: pointer;*/
            overflow:hidden;
        }
        .innerbox{
            overflow-x: hidden;
            overflow-y: auto;
            color: #000;
            font-size: .7rem;
            font-family: "\5FAE\8F6F\96C5\9ED1",Helvetica,"黑体",Arial,Tahoma;
            height: 100%;
        }
        /* scroll bar style */
        .innerbox::-webkit-scrollbar {/*The overall style of the scrollbar*/
            width: 4px; /*The height and width correspond to the size of the horizontal and vertical scroll bars*/
            height: 4px;
        }
        .innerbox::-webkit-scrollbar-thumb {/*Small square inside the scrollbar*/
            border-radius: 5px;
            -webkit-box-shadow: inset 0 0 5px rgba(0,0,0,0.2);
            background: rgba(0,0,0,0.2);
        }
        .innerbox::-webkit-scrollbar-track {/*The track inside the scrollbar*/
            -webkit-box-shadow: inset 0 0 5px rgba(0,0,0,0.2);
            border-radius: 0;
            background: rgba(0,0,0,0.1);
        }