Protocolo/public/bundles/sonatatwig/css/flashmessage.css

.read-more-state {
    display: none;
}

.read-more-target {
    opacity: 0;
    display: none;
    max-height: 0;
    font-size: 0;
    transition: .40s ease;
}

.read-more-state:checked ~ .read-more-wrap .read-more-target {
    opacity: 1;
    display: block;
    font-size: inherit;
    max-height: 999em;
}

.read-more-trigger {
    cursor: pointer;
    margin: auto;
}

.alert .read-more-trigger {
    position: relative;
    left: calc(50% - 1rem);
}