* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Arial', sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

.container {
    max-width: 800px;
    width: 100%;
    padding: 20px;
}

header {
    text-align: center;
    margin-bottom: 30px;
}

h1 {
    color: white;
    font-size: 2.5rem;
    margin-bottom: 20px;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
}

.score-board {
    display: flex;
    justify-content: center;
    gap: 30px;
    color: white;
    font-size: 1.2rem;
}

.game-area {
    background: white;
    border-radius: 20px;
    padding: 30px;
    box-shadow: 0 15px 35px rgba(0,0,0,0.1);
}

.card-container {
    display: flex;
    justify-content: center;
    margin-bottom: 30px;
    perspective: 1000px;
}

.card {
    width: 300px;
    height: 200px;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s;
    cursor: pointer;
}

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

.card-front,
.card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: 15px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.8rem;
    font-weight: bold;
    text-align: center;
    box-shadow: 0 8px 25px rgba(0,0,0,0.15);
}

.card-front {
    background: linear-gradient(135deg, #ffecd2 0%, #fcb69f 100%);
    color: #333;
}

.card-back {
    background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
    color: #333;
    transform: rotateY(180deg);
}

.options-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
    margin-bottom: 30px;
}

.option-btn {
    padding: 15px 20px;
    border: none;
    border-radius: 10px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    font-size: 1.1rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.option-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.option-btn.correct {
    background: linear-gradient(135deg, #56ab2f 0%, #a8e6cf 100%);
}

.option-btn.incorrect {
    background: linear-gradient(135deg, #ff416c 0%, #ff4b2b 100%);
}

.option-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

.controls {
    display: flex;
    justify-content: center;
    gap: 15px;
    flex-wrap: wrap;
}

.control-btn {
    padding: 12px 24px;
    border: none;
    border-radius: 25px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.control-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.feedback {
    text-align: center;
    margin-top: 20px;
    font-size: 1.2rem;
    font-weight: bold;
    min-height: 30px;
}

.feedback.correct {
    color: #28a745;
}

.feedback.incorrect {
    color: #dc3545;
}

@media (max-width: 600px) {
    .container {
        padding: 10px;
    }
    
    h1 {
        font-size: 2rem;
    }
    
    .card {
        width: 250px;
        height: 160px;
    }
    
    .card-front,
    .card-back {
        font-size: 1.4rem;
    }
    
    .options-container {
        grid-template-columns: 1fr;
    }
    
    .controls {
        flex-direction: column;
        align-items: center;
    }
    
    .control-btn {
        width: 200px;
    }
}