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

:root {
    --primary-color: #2196F3;
    --success-color: #4CAF50;
    --warning-color: #FFC107;
    --danger-color: #F44336;
    --purple-color: #9C27B0;
    --background-color: #f5f7fa;
    --surface-color: #ffffff;
    --text-primary: #333333;
    --text-secondary: #666666;
    --border-color: #e0e0e0;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 4px 20px rgba(0, 0, 0, 0.15);
    --border-radius: 12px;
    --transition: all 0.3s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: var(--background-color);
    color: var(--text-primary);
    line-height: 1.6;
    padding-bottom: 80px;
}

/* Header */
.app-header {
    background: linear-gradient(135deg, var(--primary-color), var(--purple-color));
    color: white;
    padding: 1rem;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
}

.header-content h1 {
    font-size: 1.5rem;
    font-weight: 600;
}

.user-info {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.profile-btn {
    background: none;
    border: none;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
    transition: var(--transition);
}

.profile-btn:hover {
    transform: scale(1.1);
}

/* Main Content */
.app-main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem;
}

.app-section {
    display: none;
    animation: fadeIn 0.3s ease;
}

.app-section.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Welcome Card */
.welcome-card {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow);
    text-align: center;
}

.welcome-card h2 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.8rem;
}

.welcome-card p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    font-size: 1.1rem;
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: linear-gradient(135deg, var(--primary-color), var(--purple-color));
    color: white;
    padding: 1.5rem;
    border-radius: var(--border-radius);
    text-align: center;
}

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

.stat-label {
    font-size: 0.9rem;
    opacity: 0.9;
}

/* Quick Actions */
.quick-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.action-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem 2rem;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
}

.action-btn.primary {
    background: var(--primary-color);
    color: white;
}

.action-btn.secondary {
    background: var(--success-color);
    color: white;
}

.action-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

/* Skill Categories */
.skill-categories {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow);
}

.skill-categories h3 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    font-size: 1.4rem;
}

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

.category-card {
    background: var(--surface-color);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
}

.category-card:hover {
    border-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

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

.category-card h4 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.category-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Quiz Styles */
.quiz-container {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.quiz-header {
    background: linear-gradient(135deg, var(--primary-color), var(--purple-color));
    color: white;
    padding: 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.back-btn {
    background: none;
    border: none;
    color: white;
    font-size: 1.2rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 50%;
    transition: var(--transition);
}

.back-btn:hover {
    background: rgba(255, 255, 255, 0.2);
}

.quiz-info {
    flex: 1;
}

.quiz-info h2 {
    margin-bottom: 0.5rem;
}

.quiz-progress {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.progress-bar {
    flex: 1;
    height: 8px;
    background: rgba(255, 255, 255, 0.3);
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--warning-color);
    transition: width 0.3s ease;
}

.quiz-content {
    padding: 2rem;
}

.quiz-selection h3 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    text-align: center;
}

.quiz-categories {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
}

.quiz-category-btn {
    background: var(--surface-color);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
}

.quiz-category-btn:hover {
    border-color: var(--primary-color);
    background: var(--primary-color);
    color: white;
}

.question-card {
    text-align: center;
}

.question-card h3 {
    color: var(--primary-color);
    margin-bottom: 2rem;
    font-size: 1.3rem;
    line-height: 1.5;
}

.question-options {
    display: grid;
    gap: 1rem;
    margin-bottom: 2rem;
}

.option-btn {
    background: var(--surface-color);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1rem;
    cursor: pointer;
    transition: var(--transition);
    text-align: left;
    font-size: 1rem;
}

.option-btn:hover {
    border-color: var(--primary-color);
}

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

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

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

.quiz-actions {
    text-align: center;
}

.btn {
    padding: 1rem 2rem;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.btn.primary {
    background: var(--primary-color);
    color: white;
}

.btn.secondary {
    background: var(--success-color);
    color: white;
}

.btn.outline {
    background: transparent;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

/* Quiz Results */
.results-card {
    text-align: center;
}

.results-card h3 {
    color: var(--success-color);
    margin-bottom: 2rem;
    font-size: 1.5rem;
}

.score-display {
    margin-bottom: 2rem;
}

.score-circle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 120px;
    height: 120px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--success-color), var(--warning-color));
    color: white;
    font-size: 1.5rem;
    font-weight: bold;
    margin-bottom: 1rem;
}

.results-details p {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.results-stats {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 2rem;
}

.result-stat {
    text-align: center;
}

.stat-value {
    display: block;
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

.stat-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.results-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

/* Progress Styles */
.progress-container {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow);
}

.progress-container h2 {
    color: var(--primary-color);
    margin-bottom: 2rem;
    text-align: center;
}

.progress-overview {
    margin-bottom: 2rem;
}

.overview-card {
    background: linear-gradient(135deg, var(--primary-color), var(--purple-color));
    color: white;
    border-radius: var(--border-radius);
    padding: 2rem;
    text-align: center;
}

.overview-card h3 {
    margin-bottom: 1.5rem;
}

.skill-level-display {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
}

.level-circle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100px;
    height: 100px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    font-weight: bold;
}

.level-info {
    flex: 1;
    min-width: 200px;
}

.xp-bar {
    width: 100%;
    height: 10px;
    background: rgba(255, 255, 255, 0.3);
    border-radius: 5px;
    overflow: hidden;
    margin: 1rem 0;
}

.xp-fill {
    height: 100%;
    background: var(--warning-color);
    transition: width 0.3s ease;
}

.skills-breakdown {
    margin-bottom: 2rem;
}

.skills-breakdown h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.skills-chart {
    display: grid;
    gap: 1rem;
}

.skill-item {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.skill-name {
    font-weight: 600;
    color: var(--text-primary);
}

.skill-score {
    font-weight: bold;
    color: var(--primary-color);
}

.recent-assessments {
    margin-bottom: 2rem;
}

.recent-assessments h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.assessments-list {
    display: grid;
    gap: 1rem;
}

.assessment-item {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.assessment-info h4 {
    color: var(--primary-color);
    margin-bottom: 0.25rem;
}

.assessment-info p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.assessment-score {
    font-weight: bold;
    color: var(--success-color);
}

.achievements h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.achievements-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
}

.achievement-item {
    background: var(--surface-color);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1rem;
    text-align: center;
    transition: var(--transition);
}

.achievement-item.earned {
    border-color: var(--warning-color);
    background: linear-gradient(135deg, var(--warning-color), var(--success-color));
    color: white;
}

.achievement-icon {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.achievement-title {
    font-size: 0.9rem;
    font-weight: 600;
}

/* Analysis Styles */
.analysis-container {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow);
}

.analysis-container h2 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    text-align: center;
}

.analysis-header {
    text-align: center;
    margin-bottom: 2rem;
}

.analysis-header p {
    color: var(--text-secondary);
}

.gap-analysis {
    margin-bottom: 2rem;
}

.gap-item {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 1rem;
}

.gap-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.gap-skill {
    font-weight: 600;
    color: var(--primary-color);
}

.gap-level {
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
}

.gap-level.low {
    background: var(--danger-color);
    color: white;
}

.gap-level.medium {
    background: var(--warning-color);
    color: white;
}

.gap-level.high {
    background: var(--success-color);
    color: white;
}

.gap-description {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.gap-resources {
    display: grid;
    gap: 0.5rem;
}

.resource-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--primary-color);
    text-decoration: none;
    font-size: 0.9rem;
    padding: 0.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.resource-link:hover {
    background: var(--primary-color);
    color: white;
}

.learning-path h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.learning-path-content {
    display: grid;
    gap: 1rem;
}

.path-step {
    background: var(--surface-color);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1rem;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.step-number {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--primary-color);
    color: white;
    font-weight: bold;
}

.step-content h4 {
    color: var(--primary-color);
    margin-bottom: 0.25rem;
}

.step-content p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.peer-comparison h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.peer-chart {
    display: grid;
    gap: 1rem;
}

.peer-skill {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1rem;
}

.peer-skill-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
}

.peer-skill-name {
    font-weight: 600;
    color: var(--primary-color);
}

.peer-comparison-bar {
    height: 20px;
    background: var(--border-color);
    border-radius: 10px;
    overflow: hidden;
    position: relative;
}

.peer-your-score,
.peer-average-score {
    height: 100%;
    position: absolute;
    top: 0;
    border-radius: 10px;
}

.peer-your-score {
    background: var(--primary-color);
    z-index: 2;
}

.peer-average-score {
    background: var(--text-secondary);
    z-index: 1;
}

/* Certificates Styles */
.certificates-container {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow);
}

.certificates-container h2 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    text-align: center;
}

.certificates-header {
    text-align: center;
    margin-bottom: 2rem;
}

.certificates-header p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.certificates-stats {
    color: var(--primary-color);
    font-weight: 600;
}

.certificates-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}

.certificate-card {
    background: linear-gradient(135deg, var(--warning-color), var(--success-color));
    color: white;
    border-radius: var(--border-radius);
    padding: 2rem;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.certificate-card::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><circle cx="50" cy="50" r="2" fill="rgba(255,255,255,0.1)"/></svg>') repeat;
    animation: sparkle 20s linear infinite;
}

@keyframes sparkle {
    0% { transform: translateX(0) translateY(0) rotate(0deg); }
    100% { transform: translateX(-50px) translateY(-50px) rotate(360deg); }
}

.certificate-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    position: relative;
    z-index: 1;
}

.certificate-title {
    font-size: 1.2rem;
    font-weight: bold;
    margin-bottom: 0.5rem;
    position: relative;
    z-index: 1;
}

.certificate-details {
    font-size: 0.9rem;
    opacity: 0.9;
    margin-bottom: 1rem;
    position: relative;
    z-index: 1;
}

.certificate-actions {
    position: relative;
    z-index: 1;
}

.certificate-btn {
    background: rgba(255, 255, 255, 0.2);
    border: 1px solid rgba(255, 255, 255, 0.3);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    margin: 0 0.25rem;
}

.certificate-btn:hover {
    background: rgba(255, 255, 255, 0.3);
}

.certificates-empty {
    text-align: center;
    padding: 3rem;
}

.empty-state i {
    font-size: 4rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.empty-state h3 {
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.empty-state p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

/* FAQ Styles */
.faq-section {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    padding: 2rem;
    margin: 2rem 0;
    box-shadow: var(--shadow);
}

.faq-section h2 {
    color: var(--primary-color);
    margin-bottom: 2rem;
    text-align: center;
}

.faq-container {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    margin-bottom: 1rem;
    overflow: hidden;
}

.faq-question {
    width: 100%;
    background: var(--surface-color);
    border: none;
    padding: 1.5rem;
    text-align: left;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: var(--transition);
}

.faq-question:hover {
    background: var(--background-color);
}

.faq-question[aria-expanded="true"] {
    background: var(--primary-color);
    color: white;
}

.faq-icon {
    font-size: 1.2rem;
    font-weight: bold;
    transition: transform 0.3s ease;
}

.faq-question[aria-expanded="true"] .faq-icon {
    transform: rotate(45deg);
}

.faq-answer {
    padding: 0 1.5rem;
    max-height: 0;
    overflow: hidden;
    transition: all 0.3s ease;
}

.faq-answer:not([hidden]) {
    padding: 1.5rem;
    max-height: 200px;
}

.faq-answer p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Bottom Navigation */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--surface-color);
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-around;
    padding: 0.5rem 0;
    z-index: 1000;
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-decoration: none;
    color: var(--text-secondary);
    padding: 0.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
    min-width: 60px;
}

.nav-item i {
    font-size: 1.2rem;
    margin-bottom: 0.25rem;
}

.nav-item span {
    font-size: 0.7rem;
    font-weight: 600;
}

.nav-item.active {
    color: var(--primary-color);
    background: rgba(33, 150, 243, 0.1);
}

.nav-item:hover {
    color: var(--primary-color);
}

/* Footer */
footer {
    background: var(--text-primary);
    color: white;
    text-align: center;
    padding: 1rem;
    font-size: 0.9rem;
    margin-top: 2rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .app-main {
        padding: 0.5rem;
    }
    
    .welcome-card,
    .skill-categories,
    .quiz-container,
    .progress-container,
    .analysis-container,
    .certificates-container {
        padding: 1rem;
    }
    
    .stats-grid {
        grid-template-columns: repeat(auto-fit, minmax(100px, 1fr));
    }
    
    .categories-grid {
        grid-template-columns: 1fr;
    }
    
    .quiz-categories {
        grid-template-columns: 1fr;
    }
    
    .results-actions {
        flex-direction: column;
    }
    
    .skill-level-display {
        flex-direction: column;
        text-align: center;
    }
    
    .certificates-grid {
        grid-template-columns: 1fr;
    }
    
    .quick-actions {
        flex-direction: column;
    }
    
    .action-btn {
        width: 100%;
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .header-content h1 {
        font-size: 1.2rem;
    }
    
    .welcome-card h2 {
        font-size: 1.4rem;
    }
    
    .nav-item span {
        font-size: 0.6rem;
    }
    
    .faq-question {
        padding: 1rem;
        font-size: 0.9rem;
    }
    
    .faq-answer:not([hidden]) {
        padding: 1rem;
    }
}

/* Loading and Animation States */
.loading {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.fade-in {
    animation: fadeIn 0.5s ease;
}

.slide-up {
    animation: slideUp 0.3s ease;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Utility Classes */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }
.mb-1 { margin-bottom: 1rem; }
.mb-2 { margin-bottom: 2rem; }
.mt-1 { margin-top: 1rem; }
.mt-2 { margin-top: 2rem; }
.hidden { display: none; }
.visible { display: block; }