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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: #333;
    background: #f5f5f5;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 2rem 0;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.logo {
    font-size: 2rem;
    font-weight: bold;
    margin-bottom: 0.5rem;
}

.tagline {
    font-size: 1.1rem;
    opacity: 0.9;
}

.nav {
    background: white;
    padding: 1rem 0;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
}

.nav-links a {
    color: #667eea;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

.nav-links a:hover {
    color: #764ba2;
}

.hero {
    background: white;
    padding: 3rem 0;
    text-align: center;
}

.hero h1 {
    font-size: 2.5rem;
    color: #333;
    margin-bottom: 1rem;
}

.hero p {
    font-size: 1.2rem;
    color: #666;
    max-width: 800px;
    margin: 0 auto 2rem;
}

.cta-button {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 1rem 2.5rem;
    border: none;
    border-radius: 50px;
    font-weight: bold;
    font-size: 1.1rem;
    cursor: pointer;
    transition: transform 0.3s, box-shadow 0.3s;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
}

.cta-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.6);
}

.features {
    background: white;
    padding: 3rem 0;
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.feature-item {
    text-align: center;
    padding: 1.5rem;
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.feature-item h3 {
    color: #667eea;
    margin-bottom: 0.5rem;
}

.section {
    padding: 3rem 0;
}

.alt-bg {
    background: white;
}

.section-title {
    font-size: 2rem;
    color: #333;
    margin-bottom: 0.5rem;
    font-weight: 700;
}

.section-subtitle {
    color: #666;
    margin-bottom: 2rem;
}

.test-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.test-card {
    background: white;
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 4px 6px rgba(0,0,0,0.07);
    transition: transform 0.3s, box-shadow 0.3s;
    cursor: pointer;
    border: 2px solid transparent;
}

.test-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 15px rgba(0,0,0,0.1);
    border-color: #667eea;
}

.test-card h3 {
    color: #667eea;
    font-size: 1.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
}

.exam-card {
    background: linear-gradient(135deg, #667eea15 0%, #764ba215 100%);
    border: 2px solid #667eea;
}

.test-card p {
    color: #666;
    margin-bottom: 1rem;
}

.badge {
    display: inline-block;
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.badge-easy {
    background: #d4edda;
    color: #155724;
}

.badge-hard {
    background: #fff3cd;
    color: #856404;
}

.badge-exam {
    background: #d1ecf1;
    color: #0c5460;
}

.badge-hardest {
    background: #f8d7da;
    color: #721c24;
}

.quiz-container {
    display: none;
    background: white;
    border-radius: 12px;
    padding: 2rem;
    max-width: 900px;
    margin: 2rem auto;
    box-shadow: 0 4px 6px rgba(0,0,0,0.07);
    min-height: 500px;
}

.quiz-container.active {
    display: block;
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: #e9ecef;
    border-radius: 4px;
    margin-bottom: 2rem;
    overflow: hidden;
}

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

#question-number {
    color: #667eea;
    margin-bottom: 1rem;
}

.question {
    font-size: 1.3rem;
    color: #333;
    margin-bottom: 2rem;
    font-weight: 500;
}

.question-image {
    display: flex;
    justify-content: center;
    margin: 2rem 0;
    padding: 2rem;
    background: #f8f9fa;
    border-radius: 12px;
}

.question-image img {
    max-width: 250px;
    max-height: 250px;
    width: auto;
    height: auto;
    object-fit: contain;
    border-radius: 8px;
}

.options {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.option {
    padding: 1.2rem;
    background: #f8f9fa;
    border: 2px solid #e9ecef;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
}

.option:hover {
    background: #e9ecef;
    border-color: #667eea;
}

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

.option.correct {
    background: #28a745;
    color: white;
    border-color: #28a745;
}

.option.incorrect {
    background: #dc3545;
    color: white;
    border-color: #dc3545;
}

.option.disabled {
    cursor: not-allowed;
}

.explanation {
    background: #f8f9fa;
    padding: 1.5rem;
    border-radius: 8px;
    margin-top: 1.5rem;
    border-left: 4px solid #667eea;
    display: none;
}

.explanation.show {
    display: block;
}

.explanation h4 {
    color: #667eea;
    margin-bottom: 0.5rem;
}

.quiz-controls {
    display: flex;
    justify-content: space-between;
    margin-top: 2rem;
    gap: 1rem;
}

.btn-group {
    display: flex;
    gap: 1rem;
}

.btn {
    padding: 0.8rem 2rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
}

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

.btn-primary:hover {
    background: #5568d3;
}

.btn-secondary {
    background: #6c757d;
    color: white;
}

.btn-secondary:hover {
    background: #5a6268;
}

#prev-btn, #submit-btn {
    display: none;
}

.score-display {
    text-align: center;
    padding: 2rem;
}

.score-display h2 {
    font-size: 2.5rem;
    color: #667eea;
    margin-bottom: 1rem;
}

#score-result {
    font-size: 3rem;
    font-weight: bold;
    margin: 2rem 0;
}

.pass {
    color: #28a745;
}

.fail {
    color: #dc3545;
}

#score-breakdown {
    margin-top: 2rem;
    text-align: left;
    background: #f8f9fa;
    padding: 2rem;
    border-radius: 8px;
}

.result-actions {
    margin-top: 2rem;
    display: flex;
    gap: 1rem;
    justify-content: center;
}

.faq-section {
    background: white;
    padding: 4rem 0;
}

.faq-container {
    max-width: 900px;
    margin: 2rem auto 0;
}

.faq-item {
    background: #f8f9fa;
    border-left: 4px solid #667eea;
    padding: 1.5rem 2rem;
    margin-bottom: 1.5rem;
    border-radius: 8px;
    transition: all 0.3s;
}

.faq-item:hover {
    background: #e9ecef;
    transform: translateX(5px);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.15);
}

.faq-question {
    color: #667eea;
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.8rem;
}

.faq-answer {
    color: #555;
    line-height: 1.8;
    margin: 0;
}

.footer {
    background: #2d3748;
    color: white;
    padding: 2rem 0;
    text-align: center;
    margin-top: 3rem;
}

@media (max-width: 768px) {
    .hero h1 {
        font-size: 2rem;
    }
    .test-grid {
        grid-template-columns: 1fr;
    }
    .quiz-controls {
        flex-direction: column;
    }
    .btn-group {
        flex-direction: column;
    }
}