app-test/src/app/chat/fm-bubble/fm-bubble.component.scss

.bubble {
    width: 100px;
    height: 100px;
    background-color: #3498db;
    border-radius: 50%;
    animation: breathe 1.5s infinite alternate;
}

@keyframes breathe {
    0% {
        transform: scale(0.5);
    }
    100% {
        transform: scale(1);
    }
}