body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: #f4f4f9;
    margin: 0;
}

.flashcard {
    background: #fff;
    border-radius: 8px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
    padding: 20px;
    text-align: center;
    width: 80%;
    max-width: 400px;
    opacity: 1;
}

.content {
    margin-bottom: 20px;
}

.navigation {
    display: flex;
    justify-content: space-around;
    align-items: center;
}

.nav-button {
    background: #007BFF;
    border: none;
    border-radius: 4px;
    color: #fff;
    cursor: pointer;
    font-size: 16px;
    padding: 10px 20px;
    margin: 5px;
    flex: 1;
    transition: background 0.3s;
}

.nav-button:hover {
    background: #0056b3;
}

.flip-button {
    background: #28a745;
    border: none;
    border-radius: 50%;
    color: #fff;
    cursor: pointer;
    font-size: 20px;
    padding: 15px;
    margin: 5px;
    transition: transform 0.3s, background 0.3s;
    animation: pulse 2s infinite;
}

.flip-button:hover {
    background: #218838;
    transform: scale(1.1);
}

@keyframes pulse {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.1);
    }
    100% {
        transform: scale(1);
    }
}