body {
            height: 100vh;
        }
        .app-design{
            width: 300px;
            height: 550px;
            margin: auto; 
            background-color: rgba(0, 0, 255, 0.616);
            border-radius: 30px;

        }
        #spinner{
            display: none;
            position: absolute;
            top: 48%;
            left: 49%;
        }
        #not-found{
            display: none;
        }