/* 导航栏居中*/
#nav .menus_items {
    /* display: inline; 这个带不带都可以，本来就是inline */
    position: absolute;
    width: fit-content;
    left: 50%;
    transform: translateX(-50%);
}

/* 子菜单横向*/
#nav .menus_items .menus_item:hover .menus_item_child{
  display: flex;
}