.bookshelf .thumb {
            display: inline-block;
            cursor: pointer;
            margin: 0 0.5%;
            width: calc(20% - 10px) !important;
            box-shadow: 0px 10px 10px rgba(0, 0, 0, 0.24);
            max-width: 150px;
        }

        .bookshelf .thumb img {
            width: 100%;
            display: block;
            vertical-align: top;
        }

        .bookshelf .shelf-img {
            z-index: 0;
            height: auto;
            max-width: 100%;
            vertical-align: top;
            margin-top: -12px;
        }

        .bookshelf .covers {
            width: 100%;
            height: auto;
            z-index: 99;
            position: relative;
            text-align: center;
        }

        .bookshelf .covers>div {
            display: inline-block;
            cursor: pointer;
            width: 20%;
            position: relative;
            flex: 0 0 auto;
            transform-origin: bottom center;
            transition: transform ease 0.3s;
        }

        .bookshelf .covers>div:hover {
            transform: scale(105%);
            background: linear-gradient(90deg, rgba(255, 255, 255, 0.15) 1%, rgba(0, 0, 0, 0.15) 3%, rgba(255, 255, 255, 0.15) 5%, rgba(255, 255, 255, 0) 7%);
            box-shadow: inset 0px -1px 3px 0px #5050508c;
            content: attr(alt);
        }

        .bookshelf {
            text-align: center;
            padding: 0;
        }

        .tooltipbox {
            position: relative;
            display: inline-block;
            border-bottom: 1px dotted black;
        }

        .tooltipbox .tooltiptext {
            font-family: Verdana, sans-serif;
            color: #000;
            visibility: hidden;
            bottom: 5px;
            position: absolute;
            width: 100%;
            left: 0;
            padding: 5px;
            font-size: 0.75em;
            background: rgba(255, 255, 255, 0.9);
            box-sizing: border-box;
            display: block;
            -moz-transition: 0.2s;
            -o-transition: 0.2s;
            -webkit-transition: 0.2s;
            transition: 0.2s;
            opacity: 1;
        }

        .tooltipbox:hover .tooltiptext {
            visibility: visible;
        }

        .bookshelf .thumb {
            display: inline-block;
            cursor: pointer;
            margin: 0 0.5%;
            width: calc(20% - 10px) !important;
            box-shadow: 0px 10px 10px rgba(0, 0, 0, 0.24);
            max-width: 150px;
        }

        .bookshelf .thumb img {
            width: 100%;
            display: block;
            vertical-align: top;
        }

        .bookshelf .shelf-img {
            z-index: 0;
            height: auto;
            max-width: 100%;
            vertical-align: top;
            margin-top: -12px;
        }

        .bookshelf .covers {
            width: 100%;
            height: auto;
            z-index: 99;
            position: relative;
            text-align: center;
        }

        .bookshelf .covers>div {
            display: inline-block;
            cursor: pointer;
            width: 20%;
            position: relative;
            flex: 0 0 auto;
            transform-origin: bottom center;
            transition: transform ease 0.3s;
        }

        .bookshelf .covers>div:hover {
            transform: scale(105%);
            background: linear-gradient(90deg, rgba(255, 255, 255, 0.15) 1%, rgba(0, 0, 0, 0.15) 3%, rgba(255, 255, 255, 0.15) 5%, rgba(255, 255, 255, 0) 7%);
            box-shadow: inset 0px -1px 3px 0px #5050508c;
            content: attr(alt);
        }

        .bookshelf {
            text-align: center;
            padding: 0;
        }

        .tooltipbox {
            position: relative;
            display: inline-block;
            border-bottom: 1px dotted black;
        }

        .tooltipbox .tooltiptext {
            font-family: Verdana, sans-serif;
            color: #000;
            visibility: hidden;
            bottom: 5px;
            position: absolute;
            width: 100%;
            left: 0;
            padding: 5px;
            font-size: 0.75em;
            background: rgba(255, 255, 255, 0.9);
            box-sizing: border-box;
            display: block;
            -moz-transition: 0.2s;
            -o-transition: 0.2s;
            -webkit-transition: 0.2s;
            transition: 0.2s;
            opacity: 1;
            line-height: 1.8;
        }

        .tooltipbox:hover .tooltiptext {
            visibility: visible;
        }

        /* tablets */
        @media only screen and (max-width: 1199px) {
            .tooltipbox .tooltiptext {
                visibility: visible;
                /* font-size: 0.75em; */
                line-height: 1.5;
                padding: 2px;
            }
        }

        /* only small tablets */
        @media only screen and (min-width: 768px) and (max-width: 991px) {
            .tooltipbox .tooltiptext {
                visibility: visible;
                /* font-size: 0.75em; */
                line-height: 1.3;
                padding: 2px;
            }
        }

        /* mobile or only mobile */
        @media only screen and (max-width: 767px) {
            .tooltipbox .tooltiptext {
                visibility: visible;
                /* font-size: 0.75em; */
                line-height: 1.0;
                padding: 2px;
            }
        }