gitlab-notification/documentation/ru/docs/stylesheets/extra.css

.md-typeset .admonition,
.md-typeset details {
    border-width: 0;
    border-left-width: 4px;
}

@keyframes heart {
    0%, 40%, 80%, 100% {
        transform: scale(1);
    }
    20%, 60% {
        transform: scale(1.15);
    }
}
.heart {
    animation: heart 1000ms infinite;
}