<div th:fragment="css">
    <link rel="stylesheet" href="/mobile/layui/css/layui.css">
    <style type="text/css">
        .app {
            display: none;
        }

        @media (max-width: 500px) {
            .app {
                display: block !important;
            }
        }

        .pc {
            display: block;
        }

        @media (max-width: 500px) {
            .pc {
                display: none;
            }
        }
    </style>
</div>