.ex-slide {
    overflow: hidden;
    max-height: 0;
    opacity: 0;
    transition: max-height 0.3s ease, opacity 0.3s ease;
}

.ex-slide.show {
    max-height: 500px;
    opacity: 1;
}

.slide {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.2s ease;
}

.slide.open {
    max-height: 500px; /* любое большое число */
}