/* Card flip animation */
.card-container {
    width: 100%;
    max-width: 400px;
    height: 280px;
    perspective: 1000px;
}

.card {
    width: 100%;
    height: 100%;
    position: relative;
    transition: transform 0.5s ease;
    transform-style: preserve-3d;
}

.card.flipped {
    transform: rotateY(180deg);
}

.card-front,
.card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
}

.card-back {
    transform: rotateY(180deg);
}

/* Mobile: make voice selector full width */
@media (max-width: 640px) {
    #play-btn-wrap {
        flex-wrap: wrap;
        justify-content: center;
    }
    #voice-select {
        width: 100%;
    }
}