.bubble {
    position: fixed;
    width: 10px;
    height: 10px;
    background-color: rgba(255, 255, 255, 0.7);
    border-radius: 50%;
    bottom: -10px;
    /* Start off-screen */
}

@keyframes bubble-rise {
    0% {
        transform: translateY(0);
    }

    100% {
        transform: translateY(-100vh);
    }
}