.mein-btf {
    width: min(100%, 560px);
    margin: 2rem auto;
    text-align: center;
    font-family: inherit;
}

.mein-btf__counter {
    margin-bottom: .65rem;
    color: #555;
    font-size: .95rem;
}

.mein-btf__card {
    display: block;
    width: 100%;
    height: 290px;
    padding: 0;
    border: 0;
    border-radius: 16px;
    background: transparent;
    perspective: 1100px;
    cursor: pointer;
    -webkit-tap-highlight-color: transparent;
}

.mein-btf__card:focus-visible {
    outline: 3px solid #178fc2;
    outline-offset: 5px;
}

.mein-btf__card-inner {
    position: relative;
    display: block;
    width: 100%;
    height: 100%;
    transition: transform .5s ease;
    transform-style: preserve-3d;
}

.mein-btf__card.is-flipped .mein-btf__card-inner {
    transform: rotateY(180deg);
}

.mein-btf__card.is-switching .mein-btf__card-inner {
    transition: none;
}

.mein-btf__face {
    position: absolute;
    inset: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: .75rem;
    padding: 1.5rem;
    border: 2px solid #9cc9dc;
    border-radius: 16px;
    box-sizing: border-box;
    background: linear-gradient(145deg, #f7fcfd, #e4f3f6);
    box-shadow: 0 8px 24px rgba(0, 0, 0, .09);
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
}

.mein-btf__face--back {
    transform: rotateY(180deg);
    background: linear-gradient(145deg, #effaf3, #dcefe4);
}

.mein-btf__letter {
    font-size: clamp(5rem, 16vw, 8rem);
    font-weight: 700;
    line-height: 1;
    color: #2e3b42;
}

.mein-btf__word {
    font-size: clamp(2rem, 7vw, 3.3rem);
    font-weight: 700;
    line-height: 1.15;
    color: #2e3b42;
    overflow-wrap: anywhere;
}

.mein-btf__reading {
    font-size: clamp(1.25rem, 4.5vw, 1.85rem);
    color: #3f555e;
}

.mein-btf__hint {
    margin-top: .35rem;
    color: #718087;
    font-size: .85rem;
}

.mein-btf__controls {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: .75rem;
    margin-top: 1rem;
}

.mein-btf__button {
    min-height: 44px;
    padding: .7rem .8rem;
    border: 1px solid #85b8cc;
    border-radius: 9px;
    background: #fff;
    color: #25343b;
    font: inherit;
    font-weight: 600;
    cursor: pointer;
}

.mein-btf__button:hover,
.mein-btf__button:focus-visible {
    background: #eaf6fa;
}

.mein-btf__button:focus-visible {
    outline: 3px solid rgba(23, 143, 194, .28);
    outline-offset: 2px;
}

@media (max-width: 480px) {
    .mein-btf__card {
        height: 250px;
    }

    .mein-btf__controls {
        gap: .45rem;
    }

    .mein-btf__button {
        padding-inline: .35rem;
        font-size: .95rem;
    }
}

@media (prefers-reduced-motion: reduce) {
    .mein-btf__card-inner {
        transition: none;
    }
}