:root {
    --primary-color: #2196F3;
    --success-color: #4CAF50;
    --warning-color: #FFC107;
    --danger-color: #F44336;
    --secondary-color: #9C27B0;
    --background-color: #f5f5f5;
    --surface-color: #ffffff;
    --text-primary: #212121;
    --text-secondary: #757575;
    --border-color: #e0e0e0;
    --shadow: 0 2px 8px rgba(0,0,0,0.1);
    --shadow-hover: 0 4px 16px rgba(0,0,0,0.15);
    --border-radius: 12px;
    --transition: all 0.3s cubic-bezier(0.4, 0.0, 0.2, 1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 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(--secondary-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;
}

.language-switcher {
    background: rgba(255,255,255,0.2);
    border: none;
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 20px;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.language-switcher:hover {
    background: rgba(255,255,255,0.3);
}

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

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

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

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

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

.section-header h2 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.section-header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Cards */
.welcome-card, .question-card, .summary-card, .feature-card, .tip-card {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.welcome-card:hover, .question-card:hover, .feature-card:hover, .tip-card:hover {
    box-shadow: var(--shadow-hover);
    transform: translateY(-2px);
}

.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;
}

/* Quick Stats */
.quick-stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 2rem;
}

.stat-card {
    text-align: center;
    padding: 1rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border-radius: var(--border-radius);
}

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

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

/* Buttons */
.cta-button, .btn-primary, .btn-secondary, .btn-danger {
    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;
    text-decoration: none;
    justify-content: center;
}

.cta-button, .btn-primary {
    background: var(--primary-color);
    color: white;
    width: 100%;
}

.cta-button:hover, .btn-primary:hover {
    background: #1976D2;
    transform: translateY(-2px);
}

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

.btn-secondary:hover {
    background: #616161;
}

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

.btn-danger:hover {
    background: #D32F2F;
}

.btn-primary:disabled, .btn-secondary:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

/* Features Grid */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1rem;
}

.feature-card {
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
}

.feature-card i {
    font-size: 3rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.feature-card h3 {
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

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

/* Audit Section */
.audit-container {
    max-width: 600px;
    margin: 0 auto;
}

.progress-bar {
    background: var(--border-color);
    height: 8px;
    border-radius: 4px;
    margin-bottom: 1rem;
    overflow: hidden;
}

.progress-fill {
    background: linear-gradient(90deg, var(--primary-color), var(--success-color));
    height: 100%;
    width: 0%;
    transition: width 0.5s ease;
}

.progress-text {
    text-align: center;
    margin-bottom: 2rem;
    color: var(--text-secondary);
    font-weight: 600;
}

.question-options {
    margin: 2rem 0;
}

.option-item {
    background: var(--surface-color);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1rem;
    margin-bottom: 1rem;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 1rem;
}

.option-item:hover {
    border-color: var(--primary-color);
    background: rgba(33, 150, 243, 0.05);
}

.option-item.selected {
    border-color: var(--primary-color);
    background: rgba(33, 150, 243, 0.1);
}

.option-radio {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    border: 2px solid var(--border-color);
    position: relative;
    flex-shrink: 0;
}

.option-item.selected .option-radio {
    border-color: var(--primary-color);
}

.option-item.selected .option-radio::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 10px;
    height: 10px;
    background: var(--primary-color);
    border-radius: 50%;
}

.question-actions {
    display: flex;
    gap: 1rem;
    justify-content: space-between;
}

.question-actions button {
    flex: 1;
}

/* Score Display */
.score-display {
    text-align: center;
    margin: 2rem 0;
}

.score-circle {
    display: inline-flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    width: 120px;
    height: 120px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary-color), var(--success-color));
    color: white;
    font-size: 2rem;
    font-weight: bold;
    margin-bottom: 1rem;
}

.score-display-small {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

.score-interpretation {
    margin: 1rem 0;
    padding: 1rem;
    border-radius: var(--border-radius);
    text-align: center;
}

.score-interpretation.excellent {
    background: rgba(76, 175, 80, 0.1);
    color: var(--success-color);
}

.score-interpretation.good {
    background: rgba(33, 150, 243, 0.1);
    color: var(--primary-color);
}

.score-interpretation.average {
    background: rgba(255, 193, 7, 0.1);
    color: var(--warning-color);
}

.score-interpretation.poor {
    background: rgba(244, 67, 54, 0.1);
    color: var(--danger-color);
}

/* Results Section */
.results-summary {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.summary-card {
    text-align: center;
    padding: 1.5rem;
}

.summary-card h3 {
    margin-bottom: 1rem;
    color: var(--text-secondary);
    font-size: 1rem;
}

.history-list {
    margin-top: 1rem;
}

.history-item {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    padding: 1rem;
    margin-bottom: 1rem;
    box-shadow: var(--shadow);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

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

.history-score {
    font-weight: bold;
    font-size: 1.2rem;
    color: var(--primary-color);
}

.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-secondary);
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

.export-section {
    display: flex;
    gap: 1rem;
    margin-top: 2rem;
}

.export-section button {
    flex: 1;
}

/* Education Section */
.tips-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.tip-card {
    cursor: pointer;
}

.tip-card h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

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

.guide-item {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    padding: 1rem;
    box-shadow: var(--shadow);
    cursor: pointer;
    transition: var(--transition);
}

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

.guide-title {
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

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

/* FAQ Section */
.faq-section {
    margin: 3rem 0;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

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

.faq-container {
    display: grid;
    gap: 1rem;
}

.faq-item {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.faq-question {
    width: 100%;
    padding: 1.5rem;
    background: none;
    border: none;
    text-align: left;
    font-size: 1.1rem;
    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: rgba(33, 150, 243, 0.05);
}

.faq-icon {
    font-size: 1.2rem;
    color: var(--primary-color);
    transition: transform 0.3s ease;
}

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

.faq-answer {
    padding: 0 1.5rem 1.5rem;
    color: var(--text-secondary);
    line-height: 1.6;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease, padding 0.3s ease;
}

.faq-answer.expanded {
    max-height: 200px;
    padding: 0 1.5rem 1.5rem;
}

/* 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;
    box-shadow: 0 -2px 8px rgba(0,0,0,0.1);
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
    padding: 0.5rem;
    text-decoration: none;
    color: var(--text-secondary);
    transition: var(--transition);
    border-radius: 8px;
    min-width: 60px;
}

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

.nav-item span {
    font-size: 0.75rem;
    font-weight: 500;
}

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

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0,0,0,0.5);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 9999;
}

.loading-overlay.show {
    display: flex;
}

.loading-spinner {
    background: var(--surface-color);
    padding: 2rem;
    border-radius: var(--border-radius);
    text-align: center;
    color: var(--primary-color);
}

.loading-spinner i {
    font-size: 2rem;
    margin-bottom: 1rem;
}

/* Toast Notification */
.toast {
    position: fixed;
    top: 20px;
    right: 20px;
    background: var(--surface-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-hover);
    padding: 1rem;
    transform: translateX(400px);
    transition: transform 0.3s ease;
    z-index: 9999;
    max-width: 300px;
}

.toast.show {
    transform: translateX(0);
}

.toast-content {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.toast.success .toast-icon {
    color: var(--success-color);
}

.toast.error .toast-icon {
    color: var(--danger-color);
}

.toast.warning .toast-icon {
    color: var(--warning-color);
}

.toast.info .toast-icon {
    color: var(--primary-color);
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem 1rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
    border-top: 1px solid var(--border-color);
    margin-top: 3rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .app-main {
        padding: 0.5rem;
    }
    
    .header-content h1 {
        font-size: 1.2rem;
    }
    
    .section-header h2 {
        font-size: 1.5rem;
    }
    
    .quick-stats {
        grid-template-columns: 1fr;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .results-summary {
        grid-template-columns: 1fr;
    }
    
    .question-actions {
        flex-direction: column;
    }
    
    .export-section {
        flex-direction: column;
    }
    
    .toast {
        right: 10px;
        left: 10px;
        max-width: none;
        transform: translateY(-100px);
    }
    
    .toast.show {
        transform: translateY(0);
    }
}

@media (max-width: 480px) {
    .welcome-card, .question-card, .summary-card, .feature-card, .tip-card {
        padding: 1rem;
    }
    
    .stat-number {
        font-size: 1.5rem;
    }
    
    .score-circle {
        width: 100px;
        height: 100px;
        font-size: 1.5rem;
    }
    
    .nav-item span {
        display: none;
    }
}

/* Animations */
@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

.pulse {
    animation: pulse 2s infinite;
}

@keyframes slideUp {
    from { transform: translateY(30px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

.slide-up {
    animation: slideUp 0.5s ease-out;
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Focus styles */
button:focus, .nav-item:focus, .option-item:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --shadow: 0 2px 4px rgba(0,0,0,0.3);
        --border-color: #666;
    }
}