.revision-page {
    max-width: 900px;
    margin: 60px auto;
    padding: 20px;
    text-align: center;
}

.flashcard {
    perspective: 1000px;
    margin-top: 40px;
}

.flashcard-inner {
    position: relative;
    width: 100%;
    max-width: 500px;
    height: 260px;
    margin: 0 auto;
    transition: transform 0.6s;
    transform-style: preserve-3d;
    cursor: pointer;
}

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

.flashcard-front,
.flashcard-back {
    position: absolute;
    width: 100%;
    height: 100%;
    
     display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;

    text-align: center;

    padding: 30px;

    border-radius: 20px;

    backface-visibility: hidden;

    font-size: 32px;
    font-weight: 700;

    box-shadow: 0 10px 30px rgba(0,0,0,0.08);
}

.flashcard-front {
    background: white;
    color: #111;
}

.flashcard-back {
    background: #111827;
    color: white;
    transform: rotateY(180deg);
}
.next-card-btn {
    margin-top: 30px;
    padding: 14px 24px;
    border: none;
    border-radius: 12px;
    background: #111827;
    color: white;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: opacity 0.2s;
}

.next-card-btn:hover {
    opacity: 0.9;
}
.card-helper {
    margin-top: 12px;
    font-size: 14px;
    color: #666;
    font-weight: 500;
    opacity: 0.7;
}
.flashcard-progress {
    text-align: center;
    margin-bottom: 20px;
    font-size: 16px;
    font-weight: 600;
    color: #666;
}
.revision-actions {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-top: 20px;
}

.know-btn,
.review-btn,
.restart-btn {
    padding: 12px 18px;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    font-weight: 600;
}

.revision-score {
    text-align: center;
    margin-bottom: 15px;
    font-weight: 600;
}