/* ========================================
   萝卜医生 - 在线教育平台样式
   ======================================== */

/* CSS Reset & 基础样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #4F46E5;
    --primary-dark: #4338CA;
    --primary-light: #818CF8;
    --secondary-color: #10B981;
    --text-dark: #1F2937;
    --text-gray: #6B7280;
    --text-light: #9CA3AF;
    --bg-light: #F9FAFB;
    --bg-white: #FFFFFF;
    --border-color: #E5E7EB;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* 容器 */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 导航栏 */
.navbar {
    background-color: var(--bg-white);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: all 0.3s ease;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 20px;
}

.nav-brand a {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
    transition: opacity 0.3s ease;
}

.nav-brand a:hover {
    opacity: 0.85;
}

.nav-logo {
    height: 36px;
    width: auto;
    display: block;
}

.nav-brand-text {
    font-size: 20px;
    font-weight: 700;
    color: var(--primary-color);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-menu a {
    color: var(--text-dark);
    text-decoration: none;
    font-weight: 500;
    font-size: 15px;
    transition: color 0.3s ease;
    position: relative;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--primary-color);
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: width 0.3s ease;
}

.nav-menu a:hover::after,
.nav-menu a.active::after {
    width: 100%;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    cursor: pointer;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background-color: var(--text-dark);
    transition: all 0.3s ease;
}

/* 头部横幅 */
.hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 100px 0;
    text-align: center;
}

.hero-content h1 {
    font-size: 48px;
    font-weight: 800;
    margin-bottom: 16px;
}

.hero-subtitle {
    font-size: 20px;
    font-weight: 500;
    margin-bottom: 16px;
    opacity: 0.95;
}

.hero-description {
    font-size: 16px;
    max-width: 600px;
    margin: 0 auto 32px;
    opacity: 0.9;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    justify-content: center;
}

/* 按钮 */
.btn {
    display: inline-block;
    padding: 12px 32px;
    font-size: 16px;
    font-weight: 600;
    text-decoration: none;
    border-radius: var(--radius-md);
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
}

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

.btn-primary:hover {
    background-color: var(--bg-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: transparent;
    color: white;
    border: 2px solid white;
}

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

.btn-large {
    padding: 16px 48px;
    font-size: 18px;
}

.btn-full {
    width: 100%;
}

/* 区块样式 */
.features,
.app-intro,
.stats {
    padding: 80px 0;
}

.features {
    background-color: var(--bg-light);
}

.app-intro {
    background-color: var(--bg-white);
}

/* 区块标题 */
.section-title {
    font-size: 32px;
    font-weight: 700;
    text-align: center;
    margin-bottom: 16px;
    color: var(--text-dark);
}

.section-subtitle {
    font-size: 16px;
    text-align: center;
    color: var(--text-gray);
    margin-bottom: 48px;
}

/* 功能卡片网格 */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 32px;
}

.feature-card {
    background-color: var(--bg-white);
    padding: 32px;
    border-radius: var(--radius-lg);
    text-align: center;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    color: var(--primary-color);
    margin-bottom: 20px;
    display: flex;
    justify-content: center;
}

.feature-card h3 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 12px;
}

.feature-card p {
    color: var(--text-gray);
    font-size: 14px;
    line-height: 1.6;
}

/* 应用介绍 */
.intro-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 64px;
    align-items: center;
}

.intro-text h3 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--primary-color);
}

.intro-text p {
    color: var(--text-gray);
    margin-bottom: 16px;
    line-height: 1.8;
}

.feature-list {
    list-style: none;
    margin-top: 24px;
}

.feature-list li {
    padding: 8px 0;
    padding-left: 28px;
    position: relative;
    color: var(--text-gray);
}

.feature-list li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--secondary-color);
    font-weight: 700;
}

.intro-image {
    display: flex;
    justify-content: center;
}

.app-preview {
    display: flex;
    justify-content: center;
}

.phone-frame {
    width: 240px;
    height: 480px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    border-radius: 32px;
    padding: 8px;
    box-shadow: var(--shadow-lg);
}

.phone-screen {
    width: 100%;
    height: 100%;
    background-color: var(--bg-light);
    border-radius: 24px;
    overflow: hidden;
}

.app-header {
    background-color: var(--primary-color);
    color: white;
    padding: 20px;
    text-align: center;
    font-weight: 600;
}

.app-body {
    padding: 16px;
}

.app-card {
    background-color: white;
    height: 60px;
    margin-bottom: 12px;
    border-radius: var(--radius-md);
}

.platform-highlights {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
}

.highlight-item-card {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    padding: 32px 24px;
    border-radius: var(--radius-lg);
    text-align: center;
    color: white;
    transition: all 0.3s ease;
}

.highlight-item-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.highlight-icon-large {
    font-size: 40px;
    margin-bottom: 12px;
}

.highlight-item-card h4 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 6px;
}

.highlight-item-card p {
    font-size: 13px;
    opacity: 0.9;
}

/* 数据统计 */
.stats {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 32px;
    text-align: center;
}

.stat-number {
    font-size: 42px;
    font-weight: 800;
    margin-bottom: 8px;
}

.stat-label {
    font-size: 16px;
    opacity: 0.9;
}

/* 页面头部 */
.page-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 60px 0;
    text-align: center;
}

.page-header-simple {
    background-color: var(--bg-light);
    padding: 60px 0;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
}

.page-header h1 {
    font-size: 36px;
    font-weight: 700;
    margin-bottom: 8px;
}

.page-subtitle {
    font-size: 16px;
    opacity: 0.9;
}

.update-date {
    color: var(--text-gray);
    font-size: 14px;
    margin-top: 8px;
}

/* 产品概述 */
.product-overview {
    padding: 60px 0;
    background-color: var(--bg-white);
}

.overview-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 64px;
    align-items: center;
}

.overview-text h2 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--text-dark);
}

.overview-text p {
    color: var(--text-gray);
    margin-bottom: 16px;
    line-height: 1.8;
}

.product-logo-large {
    width: 220px;
    height: 220px;
    background: #fff;
    border-radius: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.08);
}

.product-logo-img {
    width: 80%;
    height: auto;
    display: block;
    object-fit: contain;
}

/* 产品详情 */
.product-details {
    padding: 60px 0;
    background-color: var(--bg-light);
}

.details-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 32px;
}

.detail-card {
    background-color: var(--bg-white);
    padding: 32px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

.detail-card:hover {
    box-shadow: var(--shadow-md);
}

.detail-number {
    font-size: 48px;
    font-weight: 800;
    color: var(--primary-color);
    opacity: 0.2;
    margin-bottom: -16px;
}

.detail-card h3 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-dark);
}

.detail-card p {
    color: var(--text-gray);
    margin-bottom: 16px;
    line-height: 1.6;
}

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

.detail-list li {
    padding: 6px 0;
    padding-left: 20px;
    position: relative;
    font-size: 14px;
    color: var(--text-gray);
}

.detail-list li::before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--primary-color);
}

/* 课程分类 */
.course-categories {
    padding: 60px 0;
    background-color: var(--bg-white);
}

.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 24px;
}

.category-item {
    background-color: var(--bg-light);
    padding: 32px;
    border-radius: var(--radius-lg);
    text-align: center;
    transition: all 0.3s ease;
}

.category-item:hover {
    background-color: var(--primary-color);
    transform: translateY(-4px);
}

.category-item:hover h3,
.category-item:hover p,
.category-item:hover .category-icon {
    color: white;
}

.category-icon {
    font-size: 40px;
    margin-bottom: 16px;
}

.category-item h3 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-dark);
}

.category-item p {
    font-size: 14px;
    color: var(--text-gray);
}

/* 产品优势 */
.product-advantages {
    padding: 60px 0;
    background-color: var(--bg-light);
}

.advantages-list {
    max-width: 800px;
    margin: 0 auto;
}

.advantage-item {
    display: flex;
    gap: 16px;
    margin-bottom: 24px;
}

.advantage-check {
    width: 24px;
    height: 24px;
    background-color: var(--secondary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    flex-shrink: 0;
}

.advantage-text h4 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 4px;
    color: var(--text-dark);
}

.advantage-text p {
    color: var(--text-gray);
    font-size: 14px;
}

/* 特色功能 */
.feature-highlights {
    padding: 60px 0;
}

.highlight-item {
    padding: 40px 0;
    border-bottom: 1px solid var(--border-color);
}

.highlight-item:last-child {
    border-bottom: none;
}

.highlight-content {
    display: flex;
    gap: 48px;
    align-items: center;
}

.highlight-item.reverse .highlight-content {
    flex-direction: row-reverse;
}

.highlight-icon {
    color: var(--primary-color);
    flex-shrink: 0;
}

.highlight-text h2 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 16px;
    color: var(--text-dark);
}

.highlight-text p {
    color: var(--text-gray);
    margin-bottom: 16px;
    line-height: 1.8;
}

.highlight-text ul {
    list-style: none;
}

.highlight-text li {
    padding: 6px 0;
    padding-left: 20px;
    position: relative;
    color: var(--text-gray);
}

.highlight-text li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--secondary-color);
}

/* 学习体验 */
.learning-experience {
    padding: 60px 0;
    background-color: var(--bg-light);
}

.experience-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 24px;
}

.experience-card {
    background-color: var(--bg-white);
    padding: 32px;
    border-radius: var(--radius-lg);
    text-align: center;
}

.experience-number {
    font-size: 36px;
    font-weight: 800;
    color: var(--primary-color);
    opacity: 0.2;
    margin-bottom: 8px;
}

.experience-card h3 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-dark);
}

.experience-card p {
    color: var(--text-gray);
    font-size: 14px;
}

/* 技术优势 */
.tech-advantage {
    padding: 60px 0;
}

.tech-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 24px;
}

.tech-item {
    background-color: var(--bg-light);
    padding: 32px;
    border-radius: var(--radius-lg);
    text-align: center;
}

.tech-item h3 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-dark);
}

.tech-item p {
    color: var(--text-gray);
    font-size: 14px;
}

/* CTA区域 */
.cta-section {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 60px 0;
    text-align: center;
}

.cta-section h2 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 12px;
}

.cta-section p {
    font-size: 16px;
    margin-bottom: 32px;
    opacity: 0.9;
}

/* 协议内容 */
.agreement-content {
    padding: 40px 0;
    background-color: var(--bg-white);
}

.privacy-intro {
    max-width: 800px;
    margin: 0 auto 40px;
    padding: 24px;
    background-color: var(--bg-light);
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--primary-color);
}

.privacy-intro p {
    color: var(--text-gray);
    line-height: 1.8;
}

.agreement-text {
    max-width: 800px;
    margin: 0 auto;
}

.agreement-section {
    margin-bottom: 32px;
}

.agreement-section h2 {
    font-size: 22px;
    font-weight: 700;
    margin-bottom: 16px;
    color: var(--text-dark);
}

.agreement-section h3 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-dark);
}

.agreement-section p {
    color: var(--text-gray);
    margin-bottom: 12px;
    line-height: 1.8;
}

.agreement-section ul {
    list-style: none;
    margin: 12px 0;
}

.agreement-section li {
    padding: 6px 0;
    padding-left: 24px;
    position: relative;
    color: var(--text-gray);
}

.agreement-section li::before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: 700;
}

.agreement-footer {
    margin-top: 48px;
    padding: 24px;
    background-color: var(--bg-light);
    border-radius: var(--radius-lg);
    text-align: center;
}

.agreement-footer p {
    color: var(--text-gray);
    margin-bottom: 8px;
}

/* 联系我们 */
.contact-section {
    padding: 60px 0;
    background-color: var(--bg-white);
}

.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
}

.contact-info h2 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--text-dark);
}

.contact-intro {
    color: var(--text-gray);
    margin-bottom: 32px;
}

.contact-item {
    display: flex;
    gap: 16px;
    margin-bottom: 24px;
}

.contact-icon {
    color: var(--primary-color);
    flex-shrink: 0;
}

.contact-text h3 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 4px;
    color: var(--text-dark);
}

.contact-text p {
    color: var(--text-gray);
    font-size: 14px;
}

.contact-note {
    display: block;
    font-size: 12px;
    color: var(--text-light);
    margin-top: 4px;
}

.contact-address {
    margin-top: 32px;
    padding-top: 24px;
    border-top: 1px solid var(--border-color);
}

.contact-address h3 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-dark);
}

.contact-address p {
    color: var(--text-gray);
    font-size: 14px;
}

/* 联系表单 */
.contact-form {
    background-color: var(--bg-light);
    padding: 32px;
    border-radius: var(--radius-lg);
}

.contact-form h2 {
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 8px;
    color: var(--text-dark);
}

.contact-form > p {
    color: var(--text-gray);
    margin-bottom: 24px;
    font-size: 14px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-dark);
    margin-bottom: 8px;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 14px;
    font-family: inherit;
    transition: all 0.3s ease;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

.form-note {
    font-size: 12px;
    color: var(--text-light);
    text-align: center;
    margin-top: 16px;
}

/* 常见问题 */
.faq-section {
    padding: 60px 0;
    background-color: var(--bg-light);
}

.faq-list {
    display: grid;
    gap: 16px;
}

.faq-item {
    background-color: var(--bg-white);
    padding: 24px;
    border-radius: var(--radius-md);
}

.faq-item h3 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-dark);
}

.faq-item p {
    font-size: 14px;
    color: var(--text-gray);
    line-height: 1.6;
}

/* 页脚 */
.footer {
    background-color: var(--text-dark);
    color: white;
    padding: 48px 0 24px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 32px;
    margin-bottom: 32px;
}

.footer-section h4 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 16px;
}

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

.footer-section li {
    margin-bottom: 8px;
}

.footer-section a {
    color: var(--text-light);
    text-decoration: none;
    font-size: 14px;
    transition: color 0.3s ease;
}

.footer-section a:hover {
    color: white;
}

.footer-section p {
    color: var(--text-light);
    font-size: 14px;
    line-height: 1.6;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 24px;
    text-align: center;
}

.footer-bottom p {
    color: var(--text-light);
    font-size: 14px;
    margin-bottom: 8px;
}

.footer-bottom a {
    color: var(--primary-light);
    text-decoration: none;
}

.footer-bottom a:hover {
    color: white;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: var(--bg-white);
        flex-direction: column;
        padding: 16px;
        gap: 16px;
        box-shadow: var(--shadow-md);
    }

    .nav-menu.active {
        display: flex;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }

    .nav-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }

    .hero h1 {
        font-size: 32px;
    }

    .hero-subtitle {
        font-size: 16px;
    }

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .hero-buttons .btn {
        width: 100%;
        max-width: 280px;
    }

    .intro-content,
    .overview-content {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .intro-image,
    .overview-visual {
        order: -1;
    }

    .features-grid,
    .categories-grid,
    .experience-grid,
    .tech-grid {
        grid-template-columns: 1fr;
    }

    .details-grid {
        grid-template-columns: 1fr;
    }

    .highlight-content,
    .highlight-item.reverse .highlight-content {
        flex-direction: column;
        text-align: center;
    }

    .contact-grid {
        grid-template-columns: 1fr;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .section-title {
        font-size: 24px;
    }

    .footer-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 60px 0;
    }

    .hero h1 {
        font-size: 24px;
    }

    .stats-grid {
        grid-template-columns: 1fr;
    }

    .feature-card,
    .category-item,
    .experience-card,
    .tech-item {
        padding: 24px;
    }
}

/* 工具类 */
.text-center {
    text-align: center;
}

.mt-16 {
    margin-top: 16px;
}

.mb-16 {
    margin-bottom: 16px;
}

.mt-32 {
    margin-top: 32px;
}

.mb-32 {
    margin-bottom: 32px;
}