#sidebar {
        overflow: hidden;
        z-index: 3;
    }
    
    #sidebar .list-group {
        min-width: 400px;
        background-color: #333;
        min-height: 100vh;
    }
    
    #sidebar i {
        margin-right: 6px;
    }

    #sidebar .list-group-item {
        border-radius: 0;
        background-color: #333;
        color: #ccc;
        border-left: 0;
        border-right: 0;
        border-color: #2c2c2c;
        white-space: nowrap;
    }

    /* highlight active menu */
    #sidebar .list-group-item:not(.collapsed) {
        background-color: #222;
    }

    /* closed state */
    #sidebar .list-group .list-group-item[aria-expanded="false"]::after {
        content: " \f0d7";
        font-family: FontAwesome;
        display: inline;
        text-align: right;
        padding-left: 5px;
    }

    /* open state */
    #sidebar .list-group .list-group-item[aria-expanded="true"] {
    background-color: #222;
    }
    #sidebar .list-group .list-group-item[aria-expanded="true"]::after {
        content: " \f0da";
        font-family: FontAwesome;
        display: inline;
        text-align: right;
        padding-left: 5px;
    }

    /* level 1*/
    #sidebar .list-group .collapse .list-group-item,
    #sidebar .list-group .collapsing .list-group-item  {
        padding-left: 20px;
    }

    /* level 2*/
    #sidebar .list-group .collapse > .collapse .list-group-item,
    #sidebar .list-group .collapse > .collapsing .list-group-item {
        padding-left: 30px;
    }

    /* level 3*/
    #sidebar .list-group .collapse > .collapse > .collapse .list-group-item {
        padding-left: 40px;
    }

    @media (max-width:768px) {
        #sidebar {
            min-width: 35px;
            max-width: 40px;
            overflow-y: auto;
            overflow-x: visible;
            transition: all 0.25s ease;
            transform: translateX(-45px);
            position: fixed;
        }
        
        #sidebar.show {
            transform: translateX(0);
        }

        #sidebar::-webkit-scrollbar{ width: 0px; }
        
        #sidebar, #sidebar .list-group {
            min-width: 35px;
            overflow: visible;
        }
        /* overlay sub levels on small screens */
        #sidebar .list-group .collapse.show, #sidebar .list-group .collapsing {
            position: relative;
            z-index: 1;
            width: 190px;
            top: 0;
        }
        #sidebar .list-group > .list-group-item {
            text-align: center;
            padding: .75rem .5rem;
        }
        /* hide caret icons of top level when collapsed */
        #sidebar .list-group > .list-group-item[aria-expanded="true"]::after,
        #sidebar .list-group > .list-group-item[aria-expanded="false"]::after {
            display:none;
        }
    }

    .collapse.show {
        visibility: visible;
    }

    .collapsing {
        visibility: visible;
        height: 0;
        -webkit-transition-property: height, visibility;
        transition-property: height, visibility;
        -webkit-transition-timing-function: ease-out;
        transition-timing-function: ease-out;
        }
        .collapsing.width {
        -webkit-transition-property: width, visibility;
        transition-property: width, visibility;
        width: 0;
        height: 100%;
        -webkit-transition-timing-function: ease-out;
        transition-timing-function: ease-out;
    }