:root {
    --primary-color: #2b6cb0;
    --primary-hover: #2c5282;
    --background-color: #f7fafc;
    --container-bg: #ffffff;
    --text-color: #2d3748;
    --border-color: #e2e8f0;
    --correct-color: #48bb78;
    --incorrect-color: #f56565;
}

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

.container {
    background-color: var(--container-bg);
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    padding: 2rem;
    max-width: 600px;
    width: 90%;
    margin: 20px;
    text-align: center;
}

.screen {
    display: none;
}

.screen.active {
    display: block;
}

h1, h2 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 4px;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s ease;
    margin-top: 1rem;
}

button:hover:not(:disabled) {
    background-color: var(--primary-hover);
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 1.5rem;
    font-weight: bold;
    color: var(--text-color);
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
}

#options-container {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-bottom: 1.5rem;
    text-align: left;
}

.option-btn {
    background-color: #edf2f7;
    color: var(--text-color);
    border: 1px solid var(--border-color);
    padding: 12px 15px;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 1rem;
    width: 100%;
    text-align: left;
}

.option-btn:hover:not(:disabled) {
    background-color: #e2e8f0;
    border-color: #cbd5e0;
}

.option-btn.correct {
    background-color: var(--correct-color);
    color: white;
    border-color: var(--correct-color);
}

.option-btn.incorrect {
    background-color: var(--incorrect-color);
    color: white;
    border-color: var(--incorrect-color);
}

.option-btn:disabled {
    cursor: not-allowed;
    opacity: 0.8;
}

.option-btn:disabled:hover {
    background-color: #edf2f7;
    border-color: var(--border-color);
}

.option-btn.correct:disabled:hover {
    background-color: var(--correct-color);
    border-color: var(--correct-color);
}

.option-btn.incorrect:disabled:hover {
    background-color: var(--incorrect-color);
    border-color: var(--incorrect-color);
}

#feedback-container {
    margin-top: 1rem;
    padding: 1rem;
    border-radius: 4px;
    background-color: #f8fafc;
    border: 1px solid var(--border-color);
    text-align: left;
}

#feedback-container.hidden {
    display: none;
}

#feedback-title {
    margin-top: 0;
    margin-bottom: 0.5rem;
}

#feedback-title.correct {
    color: var(--correct-color);
}

#feedback-title.incorrect {
    color: var(--incorrect-color);
}

#feedback-explanation {
    margin-bottom: 1rem;
    line-height: 1.5;
}

.results-summary {
    font-size: 1.2rem;
    margin: 2rem 0;
}

#final-score {
    font-weight: bold;
    color: var(--primary-color);
    font-size: 1.5rem;
}