:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;
    --secondary-color: #10b981;
    --secondary-dark: #059669;
    --accent-color: #f59e0b;
    --danger-color: #ef4444;
    --success-color: #22c55e;
    --warning-color: #f59e0b;
    --info-color: #3b82f6;
    --bg-color: #f8fafc;
    --bg-dark: #1e293b;
    --card-bg: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-light: #94a3b8;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
    --radius-sm: 0.375rem;
    --radius: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --transition: all 0.3s ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
}

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

.navbar {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    box-shadow: var(--shadow);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.logo i {
    font-size: 1.8rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 40px;
}

.nav-menu a {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    padding: 8px 16px;
    border-radius: var(--radius);
    transition: var(--transition);
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--primary-color);
    background: rgba(99, 102, 241, 0.1);
}

.nav-user {
    display: flex;
    align-items: center;
    gap: 12px;
}

.user-name {
    color: var(--text-secondary);
    font-weight: 500;
}

.user-avatar {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    cursor: pointer;
}

.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 140px 20px 80px;
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-text h1 {
    font-size: 3rem;
    color: white;
    margin-bottom: 10px;
    font-weight: 700;
}

.hero-text h2 {
    font-size: 1.5rem;
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 20px;
    font-weight: 400;
}

.hero-desc {
    color: rgba(255, 255, 255, 0.85);
    font-size: 1.1rem;
    line-height: 1.8;
    margin-bottom: 30px;
}

.hero-stats {
    display: flex;
    gap: 40px;
    margin-bottom: 40px;
}

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

.stat-number {
    display: block;
    font-size: 2.5rem;
    font-weight: 700;
    color: white;
}

.stat-label {
    color: rgba(255, 255, 255, 0.8);
    font-size: 0.9rem;
}

.hero-actions {
    display: flex;
    gap: 20px;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 14px 28px;
    border-radius: var(--radius-lg);
    font-weight: 600;
    text-decoration: none;
    transition: var(--transition);
    cursor: pointer;
    border: none;
    font-size: 1rem;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    border: 2px solid rgba(255, 255, 255, 0.3);
}

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

.btn-lg {
    padding: 18px 36px;
    font-size: 1.1rem;
}

.hero-visual {
    position: relative;
    height: 400px;
}

.floating-cards {
    position: relative;
    width: 100%;
    height: 100%;
}

.float-card {
    position: absolute;
    background: rgba(255, 255, 255, 0.95);
    padding: 20px 30px;
    border-radius: var(--radius-xl);
    display: flex;
    align-items: center;
    gap: 15px;
    box-shadow: var(--shadow-xl);
    animation: float 3s ease-in-out infinite;
}

.float-card i {
    font-size: 2rem;
    color: var(--primary-color);
}

.float-card span {
    font-weight: 600;
    color: var(--text-primary);
}

.card-1 {
    top: 20px;
    left: 20px;
    animation-delay: 0s;
}

.card-2 {
    top: 100px;
    right: 20px;
    animation-delay: 0.5s;
}

.card-3 {
    bottom: 100px;
    left: 40px;
    animation-delay: 1s;
}

.card-4 {
    bottom: 20px;
    right: 40px;
    animation-delay: 1.5s;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-15px);
    }
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-header h2 {
    font-size: 2.5rem;
    color: var(--text-primary);
    margin-bottom: 15px;
}

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

.features {
    padding: 100px 0;
    background: white;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
}

.feature-card {
    background: var(--card-bg);
    border-radius: var(--radius-xl);
    padding: 40px;
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.feature-icon {
    width: 70px;
    height: 70px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 25px;
}

.feature-icon i {
    font-size: 1.8rem;
    color: white;
}

.feature-card h3 {
    font-size: 1.4rem;
    margin-bottom: 15px;
    color: var(--text-primary);
}

.feature-card > p {
    color: var(--text-secondary);
    margin-bottom: 20px;
    line-height: 1.7;
}

.feature-list {
    list-style: none;
    margin-bottom: 25px;
}

.feature-list li {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 8px 0;
    color: var(--text-secondary);
}

.feature-list li i {
    color: var(--success-color);
}

.feature-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
}

.feature-link:hover {
    gap: 12px;
}

.workflow {
    padding: 100px 0;
    background: linear-gradient(180deg, #f8fafc 0%, #ffffff 100%);
}

.workflow-steps {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 20px;
}

.step {
    text-align: center;
    position: relative;
}

.step-number {
    font-size: 5rem;
    font-weight: 800;
    color: rgba(99, 102, 241, 0.1);
    position: absolute;
    top: -30px;
    left: 50%;
    transform: translateX(-50%);
}

.step-content {
    background: white;
    padding: 50px 40px 30px;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow);
    position: relative;
    z-index: 1;
    min-width: 250px;
}

.step-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
}

.step-icon i {
    font-size: 2rem;
    color: white;
}

.step-content h3 {
    font-size: 1.3rem;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.step-content p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.step-arrow {
    color: var(--primary-color);
    font-size: 1.5rem;
}

.knowledge-graph {
    padding: 100px 0;
    background: white;
}

.graph-container {
    position: relative;
    padding: 60px 0;
}

.graph-node {
    display: inline-flex;
    align-items: center;
    gap: 15px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    color: white;
    padding: 20px 40px;
    border-radius: 50px;
    font-size: 1.2rem;
    font-weight: 600;
    box-shadow: var(--shadow-lg);
}

.graph-node i {
    font-size: 1.5rem;
}

.main-node {
    position: absolute;
    left: 50%;
    top: 0;
    transform: translateX(-50%);
}

.graph-branches {
    display: flex;
    justify-content: space-around;
    margin-top: 120px;
    flex-wrap: wrap;
    gap: 30px;
}

.branch {
    text-align: center;
}

.branch-node {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    background: white;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
    padding: 15px 25px;
    border-radius: 50px;
    font-weight: 600;
    margin-bottom: 20px;
    box-shadow: var(--shadow);
}

.branch-node i {
    font-size: 1.2rem;
}

.leaf-nodes {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.leaf {
    background: var(--bg-color);
    padding: 10px 20px;
    border-radius: var(--radius);
    color: var(--text-secondary);
    font-size: 0.9rem;
    transition: var(--transition);
}

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

.scenarios {
    padding: 100px 0;
    background: var(--bg-color);
}

.scenarios-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 25px;
}

.scenario-card {
    background: white;
    padding: 40px 30px;
    border-radius: var(--radius-xl);
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.scenario-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.scenario-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--secondary-color), #34d399);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 25px;
}

.scenario-icon i {
    font-size: 2rem;
    color: white;
}

.scenario-card h3 {
    font-size: 1.2rem;
    margin-bottom: 15px;
    color: var(--text-primary);
}

.scenario-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
}

.advantages {
    padding: 100px 0;
    background: white;
}

.advantages-content {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 40px;
}

.advantage-item {
    display: flex;
    gap: 25px;
    padding: 30px;
    background: var(--bg-color);
    border-radius: var(--radius-xl);
    transition: var(--transition);
}

.advantage-item:hover {
    background: white;
    box-shadow: var(--shadow-lg);
}

.advantage-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--accent-color), #fbbf24);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.advantage-icon i {
    font-size: 1.5rem;
    color: white;
}

.advantage-text h3 {
    font-size: 1.2rem;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.advantage-text p {
    color: var(--text-secondary);
    line-height: 1.7;
}

.cta {
    padding: 100px 0;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    text-align: center;
}

.cta-content h2 {
    font-size: 2.5rem;
    color: white;
    margin-bottom: 15px;
}

.cta-content p {
    color: rgba(255, 255, 255, 0.9);
    font-size: 1.2rem;
    margin-bottom: 40px;
}

.cta-buttons {
    display: flex;
    justify-content: center;
    gap: 20px;
}

.footer {
    background: var(--bg-dark);
    color: white;
    padding: 60px 0 30px;
}

.footer-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    margin-bottom: 40px;
}

.footer-brand .logo {
    color: white;
    margin-bottom: 15px;
}

.footer-brand p {
    color: var(--text-light);
}

.footer-links {
    display: flex;
    gap: 60px;
}

.footer-col h4 {
    font-size: 1.1rem;
    margin-bottom: 20px;
    color: white;
}

.footer-col ul {
    list-style: none;
}

.footer-col ul li {
    margin-bottom: 12px;
}

.footer-col ul li a {
    color: var(--text-light);
    text-decoration: none;
    transition: var(--transition);
}

.footer-col ul li a:hover {
    color: white;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 30px;
    text-align: center;
    color: var(--text-light);
}

.page-header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 120px 20px 60px;
    text-align: center;
}

.page-header h1 {
    font-size: 2.5rem;
    color: white;
    margin-bottom: 15px;
}

.page-header p {
    color: rgba(255, 255, 255, 0.9);
    font-size: 1.1rem;
}

.main-content {
    padding: 60px 0;
}

.upload-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
}

.upload-box {
    background: white;
    border-radius: var(--radius-xl);
    padding: 40px;
    box-shadow: var(--shadow);
}

.upload-area {
    border: 3px dashed var(--border-color);
    border-radius: var(--radius-xl);
    padding: 60px 40px;
    text-align: center;
    transition: var(--transition);
    cursor: pointer;
    margin-bottom: 30px;
}

.upload-area:hover,
.upload-area.dragover {
    border-color: var(--primary-color);
    background: rgba(99, 102, 241, 0.05);
}

.upload-area i {
    font-size: 4rem;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.upload-area h3 {
    font-size: 1.3rem;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.upload-area p {
    color: var(--text-secondary);
    margin-bottom: 20px;
}

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

.upload-area .btn:hover {
    background: var(--primary-dark);
}

.upload-options {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}

.option-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 12px 20px;
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    cursor: pointer;
    transition: var(--transition);
    font-size: 0.95rem;
    color: var(--text-secondary);
}

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

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

.text-input-area {
    display: none;
}

.text-input-area.show {
    display: block;
}

.text-input-area textarea {
    width: 100%;
    min-height: 200px;
    padding: 20px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-lg);
    font-size: 1rem;
    font-family: inherit;
    resize: vertical;
    transition: var(--transition);
}

.text-input-area textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.preview-section {
    background: white;
    border-radius: var(--radius-xl);
    padding: 40px;
    box-shadow: var(--shadow);
}

.preview-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
}

.preview-header h3 {
    font-size: 1.3rem;
    color: var(--text-primary);
}

.preview-content {
    min-height: 300px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-light);
}

.preview-content img {
    max-width: 100%;
    max-height: 400px;
    border-radius: var(--radius);
}

.result-section {
    margin-top: 40px;
}

.result-card {
    background: white;
    border-radius: var(--radius-xl);
    padding: 40px;
    box-shadow: var(--shadow);
}

.result-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--border-color);
}

.result-stats {
    display: flex;
    gap: 30px;
}

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

.result-stat .number {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
}

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

.question-result {
    background: var(--bg-color);
    border-radius: var(--radius-lg);
    padding: 25px;
    margin-bottom: 20px;
}

.question-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 15px;
}

.question-number {
    font-weight: 600;
    color: var(--text-primary);
}

.question-status {
    padding: 5px 15px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
}

.question-status.correct {
    background: rgba(34, 197, 94, 0.1);
    color: var(--success-color);
}

.question-status.wrong {
    background: rgba(239, 68, 68, 0.1);
    color: var(--danger-color);
}

.question-content {
    color: var(--text-secondary);
    margin-bottom: 15px;
    line-height: 1.7;
}

.error-point {
    background: rgba(239, 68, 68, 0.1);
    border-left: 4px solid var(--danger-color);
    padding: 15px 20px;
    margin-bottom: 15px;
    border-radius: 0 var(--radius) var(--radius) 0;
}

.error-point strong {
    color: var(--danger-color);
}

.correct-answer {
    background: rgba(34, 197, 94, 0.1);
    border-left: 4px solid var(--success-color);
    padding: 15px 20px;
    border-radius: 0 var(--radius) var(--radius) 0;
}

.correct-answer strong {
    color: var(--success-color);
}

.summary-card {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    color: white;
    border-radius: var(--radius-xl);
    padding: 30px;
    margin-top: 30px;
}

.summary-card h4 {
    margin-bottom: 20px;
    font-size: 1.2rem;
}

.summary-stats {
    display: flex;
    gap: 40px;
}

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

.summary-stat .value {
    font-size: 2rem;
    font-weight: 700;
}

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

.practice-section {
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: 30px;
}

.sidebar {
    background: white;
    border-radius: var(--radius-xl);
    padding: 30px;
    box-shadow: var(--shadow);
    height: fit-content;
    position: sticky;
    top: 90px;
}

.sidebar-section {
    margin-bottom: 30px;
}

.sidebar-section:last-child {
    margin-bottom: 0;
}

.sidebar-section h4 {
    font-size: 1rem;
    margin-bottom: 15px;
    color: var(--text-primary);
    padding-bottom: 10px;
    border-bottom: 1px solid var(--border-color);
}

.knowledge-list {
    list-style: none;
}

.knowledge-list li {
    padding: 10px 15px;
    margin-bottom: 8px;
    background: var(--bg-color);
    border-radius: var(--radius);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.knowledge-list li:hover,
.knowledge-list li.active {
    background: var(--primary-color);
    color: white;
}

.knowledge-list li .count {
    background: rgba(0, 0, 0, 0.1);
    padding: 2px 10px;
    border-radius: 20px;
    font-size: 0.85rem;
}

.difficulty-filter {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.difficulty-btn {
    padding: 8px 16px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    background: white;
    cursor: pointer;
    transition: var(--transition);
    font-size: 0.9rem;
}

.difficulty-btn:hover,
.difficulty-btn.active {
    background: var(--primary-color);
    border-color: var(--primary-color);
    color: white;
}

.practice-main {
    background: white;
    border-radius: var(--radius-xl);
    padding: 40px;
    box-shadow: var(--shadow);
}

.practice-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--border-color);
}

.practice-info {
    display: flex;
    gap: 30px;
}

.practice-info-item {
    text-align: center;
}

.practice-info-item .value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.practice-info-item .label {
    color: var(--text-secondary);
    font-size: 0.85rem;
}

.question-card {
    background: var(--bg-color);
    border-radius: var(--radius-lg);
    padding: 30px;
    margin-bottom: 25px;
}

.question-meta {
    display: flex;
    gap: 15px;
    margin-bottom: 20px;
}

.meta-tag {
    padding: 5px 12px;
    background: white;
    border-radius: var(--radius);
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.meta-tag.difficulty-easy {
    color: var(--success-color);
}

.meta-tag.difficulty-medium {
    color: var(--warning-color);
}

.meta-tag.difficulty-hard {
    color: var(--danger-color);
}

.question-text {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-primary);
    margin-bottom: 25px;
}

.answer-options {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.answer-option {
    display: flex;
    align-items: center;
    gap: 15px;
    padding: 15px 20px;
    background: white;
    border: 2px solid var(--border-color);
    border-radius: var(--radius);
    cursor: pointer;
    transition: var(--transition);
}

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

.answer-option.selected {
    border-color: var(--primary-color);
    background: rgba(99, 102, 241, 0.1);
}

.answer-option.correct {
    border-color: var(--success-color);
    background: rgba(34, 197, 94, 0.1);
}

.answer-option.wrong {
    border-color: var(--danger-color);
    background: rgba(239, 68, 68, 0.1);
}

.option-letter {
    width: 30px;
    height: 30px;
    background: var(--bg-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    color: var(--text-secondary);
}

.answer-option.selected .option-letter {
    background: var(--primary-color);
    color: white;
}

.practice-actions {
    display: flex;
    justify-content: space-between;
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid var(--border-color);
}

.report-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
}

.report-card {
    background: white;
    border-radius: var(--radius-xl);
    padding: 30px;
    box-shadow: var(--shadow);
}

.report-card.full-width {
    grid-column: span 2;
}

.report-card h3 {
    font-size: 1.2rem;
    margin-bottom: 25px;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 10px;
}

.report-card h3 i {
    color: var(--primary-color);
}

.radar-chart {
    width: 100%;
    height: 300px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-color);
    border-radius: var(--radius-lg);
}

.chart-placeholder {
    text-align: center;
    color: var(--text-light);
}

.chart-placeholder i {
    font-size: 3rem;
    margin-bottom: 15px;
    display: block;
}

.progress-list {
    list-style: none;
}

.progress-item {
    margin-bottom: 20px;
}

.progress-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
}

.progress-label {
    color: var(--text-secondary);
}

.progress-value {
    font-weight: 600;
    color: var(--text-primary);
}

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

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--primary-light));
    border-radius: 4px;
    transition: width 0.5s ease;
}

.error-type-list {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
}

.error-type-item {
    flex: 1;
    min-width: 150px;
    background: var(--bg-color);
    padding: 20px;
    border-radius: var(--radius-lg);
    text-align: center;
}

.error-type-item .count {
    font-size: 2rem;
    font-weight: 700;
    color: var(--danger-color);
}

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

.trend-chart {
    height: 200px;
    background: var(--bg-color);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-light);
}

.recommendation-list {
    list-style: none;
}

.recommendation-item {
    display: flex;
    gap: 15px;
    padding: 20px;
    background: var(--bg-color);
    border-radius: var(--radius-lg);
    margin-bottom: 15px;
}

.recommendation-icon {
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--secondary-color), #34d399);
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.recommendation-icon i {
    color: white;
    font-size: 1.2rem;
}

.recommendation-content h4 {
    font-size: 1rem;
    margin-bottom: 5px;
    color: var(--text-primary);
}

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

.export-actions {
    display: flex;
    gap: 15px;
    margin-top: 30px;
}

.export-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 12px 24px;
    background: white;
    border: 2px solid var(--border-color);
    border-radius: var(--radius);
    cursor: pointer;
    transition: var(--transition);
    font-size: 0.95rem;
    color: var(--text-secondary);
}

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

.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.95);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    display: none;
}

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

.loading-spinner {
    width: 60px;
    height: 60px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.loading-text {
    margin-top: 20px;
    color: var(--text-secondary);
    font-size: 1.1rem;
}

.loading-progress {
    margin-top: 20px;
    width: 300px;
    text-align: center;
}

.loading-progress .progress-bar {
    height: 8px;
    background: var(--border-color);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 10px;
}

.loading-progress .progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--primary-light));
    border-radius: 4px;
    transition: width 0.3s ease;
}

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

@media (max-width: 1024px) {
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-visual {
        display: none;
    }
    
    .hero-stats {
        justify-content: center;
    }
    
    .hero-actions {
        justify-content: center;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .workflow-steps {
        flex-direction: column;
    }
    
    .step-arrow {
        transform: rotate(90deg);
    }
    
    .scenarios-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .advantages-content {
        grid-template-columns: 1fr;
    }
    
    .upload-section,
    .practice-section,
    .report-section {
        grid-template-columns: 1fr;
    }
    
    .sidebar {
        position: static;
    }
    
    .report-card.full-width {
        grid-column: span 1;
    }
}

@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }
    
    .hero-text h1 {
        font-size: 2rem;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: 20px;
    }
    
    .scenarios-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    .footer-links {
        flex-direction: column;
        gap: 30px;
    }
}