body {
    margin: 0;
    padding: 0;
    background-image: url('background.jpg');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    width: 100vw;
    height: 100vh;
    overflow: hidden;
    cursor: pointer;
}

.container {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

.join-button {
    width: 30vw;
    max-width: 320px;
    min-width: 200px;
    animation: flash 1.5s infinite;
}

@keyframes flash {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.3; }
}