* {
    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;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

.container {
    background: white;
    border-radius: 20px;
    padding: 40px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    max-width: 800px;
    width: 100%;
}

h1 {
    color: #333;
    text-align: center;
    margin-bottom: 15px;
    font-size: 28px;
}

.instructions {
    text-align: center;
    color: #666;
    margin-bottom: 30px;
    font-size: 16px;
    line-height: 1.6;
}

.number-table {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 15px;
    margin-bottom: 30px;
}

.number-cell {
    background: #f0f0f0;
    border: 3px solid #ddd;
    border-radius: 12px;
    padding: 25px 15px;
    text-align: center;
    font-size: 24px;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
    user-select: none;
}

.number-cell:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
    border-color: #999;
}

.number-cell.selected {
    background: #ffd700;
    border-color: #ffb700;
    color: #333;
}

.number-cell.correct {
    background: #4caf50;
    border-color: #45a049;
    color: white;
    animation: correct 0.5s ease;
}

.number-cell.incorrect {
    background: #f44336;
    border-color: #da190b;
    color: white;
    animation: shake 0.5s ease;
}

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

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-10px); }
    75% { transform: translateX(10px); }
}

.button-container {
    display: flex;
    gap: 15px;
    justify-content: center;
    margin-bottom: 20px;
}

button {
    background: #667eea;
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 10px;
    font-size: 16px;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
}

button:hover {
    background: #5568d3;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

button:active {
    transform: translateY(0);
}

.feedback {
    text-align: center;
    font-size: 18px;
    font-weight: bold;
    min-height: 30px;
    margin-top: 20px;
}

.feedback.success {
    color: #4caf50;
}

.feedback.error {
    color: #f44336;
}

.info-box {
    background: #e3f2fd;
    border-left: 4px solid #2196f3;
    padding: 15px;
    border-radius: 5px;
    margin-top: 20px;
}

.info-box h3 {
    color: #1976d2;
    margin-bottom: 10px;
    font-size: 18px;
}

.info-box p {
    color: #555;
    line-height: 1.6;
}

@media (max-width: 600px) {
    .number-table {
        grid-template-columns: repeat(3, 1fr);
        gap: 10px;
    }

    .number-cell {
        padding: 20px 10px;
        font-size: 20px;
    }

    h1 {
        font-size: 24px;
    }
}