.video_class_nav_box{height: 419px; overflow: auto;}
/*滚动条样式*/
.video_class_nav_box::-webkit-scrollbar {/*滚动条整体样式*/width: 6px; /*高宽分别对应横竖滚动条的尺寸*/height: 4px;}
.video_class_nav_box::-webkit-scrollbar-thumb {/*滚动条里面小方块*/border-radius: 5px;-webkit-box-shadow: inset 0 0 5px rgba(163,163,163,0.9); background: rgba(163,163,163,0.9);}
.video_class_nav_box::-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);}