body {
            background: linear-gradient(rgba(0, 0, 0, 0.7), rgba(0, 0, 0, 0.7)), url('https://source.unsplash.com/random/1920x1080?nature') no-repeat center center fixed;
            background-size: cover;
            height: 100vh;
            display: flex;
            align-items: center;
}
        .countdown {
            font-size: 3rem;
            font-weight: bold;
}