/* ============================================
   Echome AI 落地页 - 完整样式表
   ============================================ */

/* ============================================
   CSS 变量
   ============================================ */

:root {
    --primary-color: #667eea;
    --primary-dark: #764ba2;
    --primary-light: #8b9eff;
    --secondary-color: #f093fb;
    
    --text-primary: #1a1a1a;
    --text-secondary: #555555;
    --text-tertiary: #999999;
    
    --bg-primary: #ffffff;
    --bg-secondary: #f9f9f9;
    --bg-tertiary: #f0f0f0;
    --bg-dark: #1a1a1a;
    
    --border-color: #e0e0e0;
    --border-light: #f0f0f0;
    
    --spacing-xs: 4px;
    --spacing-sm: 8px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-2xl: 48px;
    --spacing-3xl: 64px;
    --spacing-4xl: 80px;
    
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.1);
    
    --transition-fast: 150ms ease;
    --transition-base: 300ms ease;
    --transition-slow: 500ms ease;
}

/* ============================================
   重置与基础
   ============================================ */

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

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    color: var(--text-primary);
}

h1 { font-size: 2.8rem; margin-bottom: 1.5rem; }
h2 { font-size: 2.2rem; margin-bottom: 1.5rem; }
h3 { font-size: 1.8rem; margin-bottom: 1rem; }
h4 { font-size: 1.4rem; margin-bottom: 0.8rem; }

p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--primary-dark);
}

ul, ol {
    margin-bottom: 1rem;
    padding-left: 1.5rem;
}

li {
    margin-bottom: 0.5rem;
}

/* ============================================
   容器
   ============================================ */

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

/* ============================================
   按钮系统
   ============================================ */

.btn {
    display: inline-block;
    padding: 12px 30px;
    border-radius: var(--radius-lg);
    text-decoration: none;
    font-weight: 600;
    font-size: 1rem;
    transition: all var(--transition-base);
    cursor: pointer;
    border: none;
    text-align: center;
    white-space: nowrap;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: #fff;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    border: 2px solid var(--primary-color);
}

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

.btn-lg {
    padding: 16px 40px;
    font-size: 1.1rem;
}

.btn-block {
    display: block;
    width: 100%;
}

/* ============================================
   顶部导航
   ============================================ */

.header {
    background: var(--bg-primary);
    box-shadow: var(--shadow-md);
    position: sticky;
    top: 0;
    z-index: 100;
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}

.logo img {
    width: 40px;
    height: 40px;
    display: block;
}

/* PC 导航 */
.nav-desktop {
    display: flex;
    gap: 30px;
    align-items: center;
}

.nav-link {
    color: var(--text-primary);
    font-weight: 500;
    transition: color var(--transition-fast);
    position: relative;
    padding-bottom: 5px;
}

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

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--primary-color);
}

.btn-download {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: #fff !important;
    padding: 10px 20px;
    border-radius: var(--radius-lg);
}

/* 手机菜单按钮 */
.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 6px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 5px;
}

.menu-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: all var(--transition-base);
}

.menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(8px, 8px);
}

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

.menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -7px);
}

/* 手机侧滑菜单 */
/* 手机侧滑菜单 */
/* 手机侧滑菜单 - 基础样式 */
.nav-mobile {
    display: none;
    position: fixed;
    right: -100%;
    top: 70px;
    width: 250px;              /* 默认宽度 */
    max-width: 75vw;
    height: calc(100vh - 70px);
    background: var(--bg-primary);
    box-shadow: -2px 0 8px rgba(0, 0, 0, 0.1);
    flex-direction: column;
    padding: 20px 0;
    transition: right var(--transition-base);
    z-index: 99;
    overflow-y: auto;
}

.nav-mobile.active {
    right: 0;
}

/* 平板设备 (768px - 1024px) */
@media (max-width: 1024px) {
    .nav-mobile {
        width: 280px;
        max-width: 70vw;
    }
}

/* 手机设备 (480px - 767px) */
@media (max-width: 767px) {
    .nav-mobile {
        width: 260px;
        max-width: 75vw;
    }
}

/* 超小屏幕 (320px - 479px) */
@media (max-width: 479px) {
    .nav-mobile {
        width: 240px;
        max-width: 85vw;
    }
}



.nav-mobile .nav-link {
    display: block;
    padding: 15px 20px;
    border-bottom: 1px solid var(--border-light);
}

.nav-mobile .nav-link.active {
    background: var(--bg-secondary);
    color: var(--primary-color);
}

/* ============================================
   Hero 区域 - 关键修复
   ============================================ */

.hero {
    position: relative;
    min-height: 600px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    background-attachment: fixed;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.85) 0%, rgba(118, 75, 162, 0.85) 100%);
    z-index: 1;
}

.hero-overlay {
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, rgba(118, 75, 162, 0.1) 100%);
    z-index: 0;
}

.hero .container {
    position: relative;
    z-index: 2;
}

.hero-wrapper {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.hero-content {
    color: #fff;
}

.hero-content h1 {
    color: #fff;
    font-size: 2.8rem;
    line-height: 1.2;
    margin-bottom: 20px;
}

.hero-subtitle {
    font-size: 1.1rem;
    line-height: 1.8;
    color: rgba(255, 255, 255, 0.95);
    margin-bottom: 30px;
}

.hero-buttons {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}

.hero-buttons .btn {
    min-width: 200px;
}

.hero-preview {
    display: flex;
    justify-content: center;
    align-items: center;
}

.hero-preview img {
    max-width: 100%;
    height: auto;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    animation: float 3s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-20px); }
}

/* ============================================
   功能区域
   ============================================ */

.features {
    padding: 80px 20px;
    background: var(--bg-primary);
}

.features h2 {
    text-align: center;
    margin-bottom: 50px;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.feature-card {
    padding: 30px;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    text-align: center;
    transition: all var(--transition-base);
    border: 1px solid var(--border-light);
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 15px;
    display: block;
}

.feature-card h3 {
    margin-bottom: 10px;
    color: var(--text-primary);
}

.feature-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin: 0;
}

/* ============================================
   下载 CTA 区域
   ============================================ */

.download-cta {
    padding: 60px 20px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: #fff;
    text-align: center;
}

.download-cta h2 {
    color: #fff;
    margin-bottom: 10px;
}

.download-cta p {
    font-size: 1.1rem;
    margin-bottom: 30px;
    opacity: 0.95;
    color: rgba(255, 255, 255, 0.9);
}

.download-buttons {
    display: flex;
    justify-content: center;
    gap: 15px;
    flex-wrap: wrap;
}

/* ============================================
   下载页面
   ============================================ */

.download-section {
    padding: 60px 20px;
}

.download-section h1 {
    text-align: center;
    margin-bottom: 20px;
}

.download-intro {
    text-align: center;
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 40px;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.download-info {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 50px;
    background: var(--bg-secondary);
    padding: 30px;
    border-radius: var(--radius-lg);
}

.info-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.info-item .label {
    font-weight: 600;
    color: var(--text-primary);
}

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

.download-buttons-group {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
    margin-bottom: 60px;
}

.download-button-card {
    padding: 30px;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 2px solid var(--border-light);
    text-align: center;
    transition: all var(--transition-base);
}

.download-button-card:hover {
    border-color: var(--primary-color);
    box-shadow: 0 10px 30px rgba(102, 126, 234, 0.2);
}

.download-button-card h3 {
    margin-bottom: 10px;
    color: var(--text-primary);
}

.download-button-card p {
    color: var(--text-secondary);
    margin-bottom: 20px;
    font-size: 0.95rem;
}

.install-guide {
    background: var(--bg-secondary);
    padding: 40px;
    border-radius: var(--radius-lg);
    margin-bottom: 50px;
}

.install-guide h2 {
    margin-bottom: 30px;
}

.guide-steps {
    list-style: none;
    counter-reset: step;
}

.guide-steps li {
    counter-increment: step;
    margin-bottom: 25px;
    padding-left: 50px;
    position: relative;
}

.guide-steps li::before {
    content: counter(step);
    position: absolute;
    left: 0;
    top: 0;
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: #fff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
}

.guide-steps strong {
    display: block;
    margin-bottom: 5px;
    color: var(--text-primary);
}

.guide-steps p {
    color: var(--text-secondary);
    margin: 0;
}

.faq-quick {
    background: var(--bg-secondary);
    padding: 40px;
    border-radius: var(--radius-lg);
}

.faq-quick h2 {
    margin-bottom: 20px;
}

.faq-list {
    list-style: none;
    padding: 0;
}

.faq-list li {
    margin-bottom: 12px;
}

.faq-list a {
    color: var(--primary-color);
    font-weight: 500;
}

.faq-list a:hover {
    text-decoration: underline;
}

/* ============================================
   应用场景页面
   ============================================ */

.scenarios-section {
    padding: 60px 20px;
}

.scenarios-section h1 {
    text-align: center;
    margin-bottom: 20px;
}

.section-intro {
    text-align: center;
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 50px;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.scenarios-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-bottom: 60px;
}

.scenario-card {
    padding: 30px;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-light);
    transition: all var(--transition-base);
}

.scenario-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.scenario-icon {
    font-size: 2.5rem;
    margin-bottom: 15px;
    display: block;
}

.scenario-card h3 {
    margin-bottom: 10px;
    color: var(--text-primary);
}

.scenario-card p {
    color: var(--text-secondary);
    margin-bottom: 15px;
    font-size: 0.95rem;
}

.link-arrow {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: all var(--transition-fast);
    display: inline-block;
}

.link-arrow:hover {
    transform: translateX(5px);
}

.scenario-cta {
    text-align: center;
    padding: 60px 20px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: #fff;
    border-radius: var(--radius-lg);
}

.scenario-cta h2 {
    color: #fff;
    margin-bottom: 10px;
}

.scenario-cta p {
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 30px;
}

/* ============================================
   FAQ 页面
   ============================================ */

.faq-section {
    padding: 60px 20px;
}

.faq-accordion {
    max-width: 900px;
    margin: 0 auto 60px;
}

.faq-category {
    margin-bottom: 50px;
}

.faq-category h2 {
    font-size: 1.5rem;
    margin-bottom: 25px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--primary-color);
}

.faq-item {
    margin-bottom: 15px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    overflow: hidden;
}

.faq-question {
    width: 100%;
    padding: 20px;
    background: var(--bg-secondary);
    border: none;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    transition: all var(--transition-fast);
}

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

.faq-question .icon {
    font-size: 1.5rem;
    transition: transform var(--transition-base);
}

.faq-item.active .faq-question {
    background: var(--primary-color);
    color: #fff;
}

.faq-item.active .faq-question .icon {
    transform: rotate(45deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-base);
    background: var(--bg-primary);
}

.faq-item.active .faq-answer {
    max-height: 500px;
    padding: 20px;
}

.faq-answer p {
    color: var(--text-secondary);
    line-height: 1.8;
    margin: 0;
}

.faq-answer ul,
.faq-answer ol {
    margin: 10px 0 0 20px;
    color: var(--text-secondary);
}

.faq-answer li {
    margin-bottom: 8px;
}

.faq-contact {
    text-align: center;
    padding: 40px;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    margin-top: 60px;
}

.faq-contact h2 {
    margin-bottom: 10px;
}

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

/* ============================================
   关于页面
   ============================================ */

.about-section {
    padding: 60px 20px;
}

.about-intro {
    max-width: 800px;
    margin: 0 auto 60px;
    text-align: center;
}

.about-intro h2 {
    margin-bottom: 20px;
}

.about-intro p {
    font-size: 1.1rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

.version-info {
    margin-bottom: 60px;
}

.version-info h2 {
    text-align: center;
    margin-bottom: 30px;
}

.version-card {
    max-width: 600px;
    margin: 0 auto;
    background: var(--bg-secondary);
    padding: 30px;
    border-radius: var(--radius-lg);
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 20px;
}

.version-item {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.version-item .label {
    font-weight: 600;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.version-item .value {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--primary-color);
}

.update-history {
    margin-bottom: 60px;
}

.update-history h2 {
    text-align: center;
    margin-bottom: 40px;
}

.timeline {
    max-width: 800px;
    margin: 0 auto;
    position: relative;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 20px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--primary-color);
}

.timeline-item {
    margin-bottom: 40px;
    padding-left: 80px;
    position: relative;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: 8px;
    top: 5px;
    width: 24px;
    height: 24px;
    background: var(--primary-color);
    border: 4px solid var(--bg-primary);
    border-radius: 50%;
    box-shadow: 0 0 0 2px var(--primary-color);
}

.timeline-date {
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 8px;
    font-size: 1rem;
}

.timeline-content h4 {
    margin-bottom: 10px;
    color: var(--text-primary);
}

.timeline-content ul {
    list-style: none;
    padding-left: 0;
}

.timeline-content li {
    color: var(--text-secondary);
    margin-bottom: 8px;
    padding-left: 20px;
    position: relative;
}

.timeline-content li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
}

.user-reviews {
    margin-bottom: 60px;
}

.user-reviews h2 {
    text-align: center;
    margin-bottom: 40px;
}

.reviews-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 25px;
}

.review-card {
    padding: 25px;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--primary-color);
}

.review-stars {
    color: #ffc107;
    font-size: 1.1rem;
    margin-bottom: 10px;
}

.review-text {
    color: var(--text-secondary);
    margin-bottom: 15px;
    font-style: italic;
    line-height: 1.6;
}

.review-author {
    color: var(--text-tertiary);
    font-size: 0.9rem;
    margin: 0;
}

.stats {
    margin-bottom: 60px;
}

.stats h2 {
    text-align: center;
    margin-bottom: 40px;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 25px;
}

.stat-card {
    text-align: center;
    padding: 30px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: #fff;
    border-radius: var(--radius-lg);
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 10px;
}

.stat-label {
    font-size: 1rem;
    opacity: 0.9;
}

.about-cta {
    text-align: center;
    padding: 60px 20px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: #fff;
    border-radius: var(--radius-lg);
}

.about-cta h2 {
    color: #fff;
    margin-bottom: 10px;
}

.about-cta p {
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 30px;
}

/* ============================================
   底部
   ============================================ */

.footer {
    background: var(--bg-dark);
    color: #fff;
    padding: 60px 20px 20px;
    margin-top: 80px;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto 30px;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
}

.footer-section h4 {
    color: #fff;
    margin-bottom: 15px;
}

.footer-section p {
    color: #aaa;
    margin-bottom: 10px;
}

.footer-section ul {
    list-style: none;
    padding: 0;
}

.footer-section li {
    margin-bottom: 10px;
}

.footer-section a {
    color: #aaa;
    text-decoration: none;
    transition: color var(--transition-fast);
}

.footer-section a:hover {
    color: var(--primary-color);
}

.footer-bottom {
    max-width: 1200px;
    margin: 0 auto;
    padding-top: 30px;
    border-top: 1px solid #333;
    text-align: center;
    color: #999;
    font-size: 0.9rem;
}

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

.footer-bottom a:hover {
    text-decoration: underline;
}

/* ============================================
   返回顶部按钮
   ============================================ */

.scroll-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: #fff;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: none;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
    transition: all var(--transition-base);
    z-index: 98;
}

.scroll-to-top:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.6);
}

.scroll-to-top.show {
    display: flex;
}

.scroll-to-top::before {
    content: '↑';
}

/* ============================================
   响应式设计 - 平板 (768px - 1024px)
   ============================================ */

@media (max-width: 1024px) {
    .container {
        padding: 0 15px;
    }

    h1 { font-size: 2rem; }
    h2 { font-size: 1.6rem; }
    h3 { font-size: 1.4rem; }

    .hero-wrapper {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .hero-content h1 {
        font-size: 2rem;
    }

    .hero-preview {
        order: -1;
    }

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

    .download-buttons-group {
        grid-template-columns: 1fr;
    }

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

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

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

/* ============================================
   响应式设计 - 手机 (320px - 767px)
   ============================================ */

@media (max-width: 767px) {
    body {
        font-size: 14px;
    }

    .container {
        padding: 0 15px;
    }

    h1 { font-size: 1.5rem; margin-bottom: 0.8rem; }
    h2 { font-size: 1.3rem; margin-bottom: 1rem; }
    h3 { font-size: 1.1rem; }

    /* 导航 */
    .nav-desktop {
        display: none;
    }

    .menu-toggle {
        display: flex;
    }

    .nav-mobile {
        display: flex;
    }

    .header-container {
        height: 60px;
    }

    /* Hero */
    .hero {
        min-height: 500px;
        background-attachment: scroll;
    }

    .hero-wrapper {
        grid-template-columns: 1fr;
        gap: 30px;
    }

    .hero-content h1 {
        font-size: 1.5rem;
    }

    .hero-subtitle {
        font-size: 0.95rem;
    }

    .hero-buttons {
        flex-direction: column;
    }

    .hero-buttons .btn {
        min-width: auto;
    }

    .hero-preview img {
        max-width: 80%;
    }

    /* 特性 */
    .features {
        padding: 40px 15px;
    }

    .features h2 {
        margin-bottom: 30px;
    }

    .features-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    /* 下载 */
    .download-section {
        padding: 40px 15px;
    }

    .download-info {
        grid-template-columns: 1fr;
        gap: 15px;
        padding: 20px;
    }

    .download-buttons-group {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .download-button-card {
        padding: 20px;
    }

    .install-guide {
        padding: 20px;
    }

    .guide-steps li {
        padding-left: 45px;
    }

    .guide-steps li::before {
        width: 35px;
        height: 35px;
        font-size: 0.9rem;
    }

    /* 场景 */
    .scenarios-section {
        padding: 40px 15px;
    }

    .scenarios-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    /* FAQ */
    .faq-section {
        padding: 40px 15px;
    }

    .faq-accordion {
        margin: 0 auto 40px;
    }

    .faq-question {
        padding: 15px;
        font-size: 0.95rem;
    }

    /* 关于 */
    .about-section {
        padding: 40px 15px;
    }

    .version-card {
        grid-template-columns: 1fr;
    }

    .timeline::before {
        left: 15px;
    }

    .timeline-item {
        padding-left: 60px;
    }

    .timeline-item::before {
        left: 3px;
    }

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

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

    /* 底部 */
    .footer-content {
        grid-template-columns: 1fr;
        gap: 30px;
    }

    .scroll-to-top {
        bottom: 20px;
        right: 20px;
        width: 45px;
        height: 45px;
        font-size: 1.2rem;
    }

    /* CTA */
    .download-cta,
    .scenario-cta,
    .about-cta {
        padding: 40px 15px;
    }

    .download-cta h2,
    .scenario-cta h2,
    .about-cta h2 {
        font-size: 1.3rem;
    }

    .btn {
        padding: 10px 20px;
        font-size: 0.9rem;
    }

    .btn-lg {
        padding: 12px 30px;
        font-size: 1rem;
    }
}

/* ============================================
   超小屏幕 (320px - 480px)
   ============================================ */

@media (max-width: 480px) {
    h1 { font-size: 1.3rem; }
    h2 { font-size: 1.1rem; }

    .header-container {
        height: 60px;
    }

    .logo span {
        display: none;
    }

    .hero-preview img {
        max-width: 100%;
    }

    .feature-card {
        padding: 20px;
    }

    .feature-icon {
        font-size: 2.5rem;
    }

    .download-button-card {
        padding: 15px;
    }

    .scenario-card {
        padding: 20px;
    }

    .review-card {
        padding: 15px;
    }

    .stat-card {
        padding: 20px;
    }

    .stat-number {
        font-size: 2rem;
    }

    .faq-question {
        padding: 12px;
    }

    .nav-mobile {
        width: 100%;
        max-width: 100%;
    }
}

/* ============================================
   打印样式
   ============================================ */

@media print {
    .header,
    .footer,
    .scroll-to-top,
    .menu-toggle,
    .nav-mobile {
        display: none;
    }

    body {
        background: white;
    }

    a {
        text-decoration: underline;
    }
}

/* ============================================
   暗黑模式支持（可选）
   ============================================ */

@media (prefers-color-scheme: dark) {
    :root {
        --bg-primary: #1a1a1a;
        --bg-secondary: #2a2a2a;
        --bg-tertiary: #3a3a3a;
        --text-primary: #ffffff;
        --text-secondary: #cccccc;
        --text-tertiary: #999999;
        --border-color: #444444;
        --border-light: #333333;
    }

    .hero {
        background-color: #1a1a1a;
    }
}