body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f4f7f6;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
}

.quiz-container {
    background: #ffffff;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    width: 90%;
    max-width: 600px;
}

.header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px solid #eee;
    font-size: 1.1em;
    font-weight: bold;
    color: #333;
}

#question-text {
    font-size: 1.5em;
    margin-bottom: 25px;
    color: #4CAF50; /* Primary color */
}

/* --- Answer Buttons Grid --- */
.btn-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr); /* Two columns */
    gap: 15px;
    margin-bottom: 20px;
}

.answer-btn {
    padding: 15px;
    font-size: 1em;
    border: 2px solid #ddd;
    border-radius: 8px;
    background-color: #f9f9f9;
    cursor: pointer;
    transition: background-color 0.2s, border-color 0.2s;
}

.answer-btn:hover:not(:disabled) {
    background-color: #e6e6e6;
    border-color: #bbb;
}

.answer-btn:disabled {
    cursor: default;
    opacity: 0.8;
}

/* --- Feedback and Result Styling --- */
.correct {
    background-color: #d4edda !important;
    border-color: #4CAF50 !important;
    color: #155724;
}

.incorrect {
    background-color: #f8d7da !important;
    border-color: #dc3545 !important;
    color: #721c24;
}

#feedback {
    margin-bottom: 15px;
    padding: 10px;
    border-radius: 5px;
    font-weight: bold;
}

/* --- Navigation Buttons --- */
#next-button, #restart-button {
    width: 100%;
    padding: 12px;
    font-size: 1.2em;
    border: none;
    border-radius: 8px;
    background-color: #4CAF50;
    color: white;
    cursor: pointer;
    margin-top: 10px;
    transition: background-color 0.2s;
}

#next-button:hover, #restart-button:hover {
    background-color: #45a049;
}

/* --- Utility Classes --- */
.hidden {
    display: none;
}

#result-screen {
    text-align: center;
    padding: 20px;
    background: #e9ecef;
    border-radius: 8px;
}

#final-score {
    font-size: 1.8em;
    margin: 20px 0;
    color: #333;
}