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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
}

header {
    background: white;
    padding: 20px;
    border-radius: 10px;
    margin-bottom: 20px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

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

.progress-bar {
    width: 100%;
    height: 20px;
    background: #e0e0e0;
    border-radius: 10px;
    overflow: hidden;
    margin-bottom: 15px;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, #667eea 0%, #764ba2 100%);
    transition: width 0.3s ease;
    width: 0%;
}

.stats {
    display: flex;
    justify-content: space-between;
    color: #666;
    font-size: 14px;
}

main {
    background: white;
    border-radius: 10px;
    padding: 30px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.welcome-screen {
    text-align: center;
}

.welcome-screen h2 {
    color: #333;
    margin-bottom: 20px;
    font-size: 32px;
}

.welcome-screen p {
    color: #666;
    font-size: 18px;
    margin-bottom: 30px;
}

.features {
    background: #f5f5f5;
    padding: 20px;
    border-radius: 8px;
    margin-bottom: 30px;
    text-align: left;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.features h3 {
    color: #333;
    margin-bottom: 15px;
}

.features ul {
    list-style: none;
    padding: 0;
}

.features li {
    color: #555;
    padding: 8px 0;
    font-size: 16px;
}

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

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 6px;
    font-size: 16px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 600;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 12px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
    background: #e0e0e0;
    color: #333;
}

.btn-secondary:hover {
    background: #d0d0d0;
}

.question-card {
    margin-bottom: 30px;
}

.question-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 2px solid #e0e0e0;
}

.question-header h3 {
    color: #333;
    font-size: 24px;
}

.bookmark-btn {
    background: transparent;
    border: 2px solid #667eea;
    color: #667eea;
    padding: 8px 16px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    transition: all 0.3s ease;
}

.bookmark-btn:hover {
    background: #667eea;
    color: white;
}

.bookmark-btn.bookmarked {
    background: #667eea;
    color: white;
}

.question-text {
    color: #333;
    font-size: 18px;
    line-height: 1.6;
    margin-bottom: 25px;
    white-space: pre-wrap;
}

.options {
    margin-bottom: 25px;
}

.option {
    background: #f9f9f9;
    border: 2px solid #e0e0e0;
    padding: 15px;
    margin-bottom: 12px;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: flex-start;
    gap: 12px;
}

.option:hover {
    border-color: #667eea;
    background: #f0f4ff;
}

.option.selected {
    border-color: #667eea;
    background: #e8f0fe;
}

.option.correct {
    border-color: #4caf50;
    background: #e8f5e9;
}

.option.incorrect {
    border-color: #f44336;
    background: #ffebee;
}

.option input[type="checkbox"],
.option input[type="radio"] {
    margin-top: 3px;
    cursor: pointer;
}

.option-label {
    flex: 1;
    color: #333;
    font-size: 16px;
    line-height: 1.5;
}

.community-info {
    background: #e3f2fd;
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 15px;
    color: #1976d2;
}

.answer-feedback {
    padding: 15px;
    border-radius: 8px;
    margin-top: 15px;
}

.answer-feedback.correct {
    background: #e8f5e9;
    border-left: 4px solid #4caf50;
    color: #2e7d32;
}

.answer-feedback.incorrect {
    background: #ffebee;
    border-left: 4px solid #f44336;
    color: #c62828;
}

.navigation {
    display: flex;
    gap: 15px;
    justify-content: center;
    margin-bottom: 30px;
    flex-wrap: wrap;
}

.question-navigator {
    border-top: 2px solid #e0e0e0;
    padding-top: 20px;
}

.question-navigator h4 {
    color: #333;
    margin-bottom: 15px;
}

.question-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(45px, 1fr));
    gap: 8px;
}

.question-number {
    width: 45px;
    height: 45px;
    border: 2px solid #e0e0e0;
    background: white;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    transition: all 0.3s ease;
}

.question-number:hover {
    border-color: #667eea;
    background: #f0f4ff;
}

.question-number.current {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

.question-number.answered {
    background: #e8f5e9;
    border-color: #4caf50;
}

.question-number.bookmarked {
    background: #fff3e0;
    border-color: #ff9800;
}

.question-number.correct {
    background: #4caf50;
    color: white;
    border-color: #4caf50;
}

.question-number.incorrect {
    background: #f44336;
    color: white;
    border-color: #f44336;
}

@media (max-width: 768px) {
    body {
        padding: 10px;
    }

    h1 {
        font-size: 22px;
    }

    .welcome-screen h2 {
        font-size: 24px;
    }

    .button-group {
        flex-direction: column;
    }

    .btn {
        width: 100%;
    }

    .navigation {
        flex-direction: column;
    }

    .question-grid {
        grid-template-columns: repeat(auto-fill, minmax(40px, 1fr));
    }

    .question-number {
        width: 40px;
        height: 40px;
    }
}