*, *::before, *::after {
    box-sizing: border-box;
    font-family: Arial, sans-serif;
}

body {
    background: #F0F2F5; /* A soft, modern background color */
    color: #333;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    padding: 20px;
}

.app-container {
    width: 100%;
    max-width: 700px;
    background-color: white;
    border-radius: 15px;
    padding: 30px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    text-align: center;
}

h1 {
    color: #4A4A4A;
    margin-bottom: 2rem;
}

.btn-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 15px;
    margin-top: 20px;
}

.btn {
    background-color: #007BFF;
    color: white;
    border: none;
    border-radius: 8px;
    padding: 15px;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s, transform 0.2s;
}

.btn:hover {
    background-color: #0056b3;
    transform: translateY(-2px);
}

.btn.correct {
    background-color: #28a745; /* Green for correct */
}

.btn.wrong {
    background-color: #dc3545; /* Red for wrong */
}

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

.start-btn, .next-btn, .restart-btn {
    font-size: 1.2rem;
    font-weight: bold;
    padding: 10px 30px;
}

#question {
    font-size: 1.5rem;
    font-weight: bold;
    margin-bottom: 1rem;
}

#score-container {
    font-size: 1.5rem;
    font-weight: bold;
}

.hide {
    display: none;
}