#flashcard-app {
    max-width: 600px;
    margin: 30px auto;
    text-align: center;
    perspective: 1000px;
}

.fc-card {
    background: white;
    height: 300px;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 1px solid #e0e0e0;
}

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

.fc-front, .fc-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 20px;
    box-sizing: border-box;
}

.fc-back {
    transform: rotateY(180deg);
    background: #fcfcfc;
    border-radius: 12px;
}

.fc-hanzi {
    font-size: 4em;
    color: #333;
    font-family: "Noto Serif SC", serif;
}

.fc-pinyin {
    font-size: 1.5em;
    color: #1565c0;
    font-weight: bold;
    margin-bottom: 10px;
}

.fc-def {
    font-size: 1.1em;
    color: #555;
    line-height: 1.4;
}

.fc-hint {
    font-size: 0.8em;
    color: #aaa;
    margin-top: 20px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.fc-controls {
    margin-top: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.fc-controls button {
    background: #444;
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 1em;
}

.fc-controls button:disabled {
    background: #ccc;
    cursor: default;
}