/* ========================================
   言途AI 官网样式表
   主题：蓝紫色系 · 科技感AI助手
   ======================================== */

/* CSS变量 */
:root {
    /* 主色调 - 蓝紫色系 */
    --primary: #6366F1;
    --primary-dark: #4F46E5;
    --primary-light: #818CF8;
    --accent: #06B6D4;
    --primary-gradient: linear-gradient(135deg, #6366F1 0%, #06B6D4 100%);
    --primary-gradient-vertical: linear-gradient(180deg, #6366F1 0%, #4F46E5 100%);

    /* 辅助色 */
    --secondary: #A78BFA;
    --success: #2ED573;
    --warning: #FFA502;
    --info: #1E90FF;

    /* 中性色 */
    --dark: #0f172a;
    --dark-2: #1e293b;
    --gray-900: #2d3436;
    --gray-800: #4a4a4a;
    --gray-700: #636e72;
    --gray-600: #747d8c;
    --gray-500: #a4b0be;
    --gray-400: #ced6e0;
    --gray-300: #dfe4ea;
    --gray-200: #f1f2f6;
    --gray-100: #f8f9fa;
    --white: #ffffff;

    /* 背景色 */
    --bg-primary: #ffffff;
    --bg-secondary: #f5f3ff;
    --bg-dark: #0f172a;
    --bg-gradient: linear-gradient(180deg, #f5f3ff 0%, #ffffff 100%);

    /* 文字色 */
    --text-primary: #2d3436;
    --text-secondary: #636e72;
    --text-muted: #a4b0be;
    --text-light: #ffffff;

    /* 边框 */
    --border-color: #e0e7ff;
    --border-radius-sm: 8px;
    --border-radius: 12px;
    --border-radius-lg: 20px;
    --border-radius-xl: 30px;
    --border-radius-full: 9999px;

    /* 阴影 */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.06);
    --shadow: 0 4px 16px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 8px 30px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 16px 50px rgba(0, 0, 0, 0.12);
    --shadow-primary: 0 8px 25px rgba(99, 102, 241, 0.3);
    --shadow-primary-lg: 0 12px 40px rgba(99, 102, 241, 0.4);

    /* 间距 */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;
    --space-2xl: 48px;
    --space-3xl: 64px;
    --space-4xl: 80px;

    /* 字体 */
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
    --font-size-xs: 12px;
    --font-size-sm: 14px;
    --font-size-base: 16px;
    --font-size-lg: 18px;
    --font-size-xl: 20px;
    --font-size-2xl: 24px;
    --font-size-3xl: 30px;
    --font-size-4xl: 36px;
    --font-size-5xl: 48px;
    --font-size-6xl: 64px;

    /* 过渡 */
    --transition-fast: 0.2s ease;
    --transition: 0.3s ease;
    --transition-slow: 0.5s ease;

    /* 容器 */
    --container-max: 1200px;
    --container-padding: 20px;

    /* 导航栏高度 */
    --navbar-height: 70px;
}

/* 重置样式 */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

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

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

ul, ol {
    list-style: none;
}

button {
    font-family: inherit;
    font-size: inherit;
    cursor: pointer;
    border: none;
    background: none;
    outline: none;
}

input, textarea {
    font-family: inherit;
    font-size: inherit;
    outline: none;
}

/* 容器 */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

/* 通用按钮 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 28px;
    font-size: var(--font-size-base);
    font-weight: 600;
    border-radius: var(--border-radius-full);
    transition: all var(--transition);
    cursor: pointer;
    white-space: nowrap;
    border: 2px solid transparent;
    line-height: 1.4;
}

.btn-icon {
    font-size: 1.2em;
    font-weight: 700;
}

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

.btn-primary:hover {
    color: var(--white);
    transform: translateY(-2px);
    box-shadow: var(--shadow-primary-lg);
}

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

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

.btn-outline:hover {
    background: var(--primary);
    color: var(--white);
    transform: translateY(-2px);
}

.btn-lg {
    padding: 16px 36px;
    font-size: var(--font-size-lg);
}

.btn-xl {
    padding: 20px 48px;
    font-size: var(--font-size-xl);
}

/* 区块通用 */
section {
    padding: var(--space-4xl) 0;
}

.section-header {
    text-align: center;
    margin-bottom: var(--space-3xl);
}

.section-tag {
    display: inline-block;
    font-size: var(--font-size-sm);
    font-weight: 700;
    letter-spacing: 3px;
    color: var(--primary);
    text-transform: uppercase;
    margin-bottom: var(--space-md);
    padding: 6px 16px;
    background: rgba(99, 102, 241, 0.1);
    border-radius: var(--border-radius-full);
}

.section-title {
    font-size: var(--font-size-4xl);
    font-weight: 800;
    color: var(--text-primary);
    margin-bottom: var(--space-md);
    line-height: 1.3;
}

.section-desc {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* ========================================
   导航栏
   ======================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--navbar-height);
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    z-index: 1000;
    transition: all var(--transition);
    border-bottom: 1px solid transparent;
}

.navbar.scrolled {
    box-shadow: var(--shadow-sm);
    border-bottom-color: var(--border-color);
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 800;
    font-size: var(--font-size-xl);
    color: var(--text-primary);
}

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

.logo-icon {
    width: 36px;
    height: 36px;
    border-radius: var(--border-radius-sm);
    object-fit: cover;
}

.logo-text {
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: var(--space-xl);
}

.nav-link {
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--text-secondary);
    position: relative;
    padding: 4px 0;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-gradient);
    transition: width var(--transition);
    border-radius: 2px;
}

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

.nav-link:hover::after {
    width: 100%;
}

.nav-download {
    padding: 10px 24px;
    font-size: var(--font-size-sm);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 8px;
}

.nav-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: all var(--transition);
}

.nav-toggle.active span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

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

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

/* ========================================
   Hero区域
   ======================================== */
.hero {
    position: relative;
    padding-top: calc(var(--navbar-height) + var(--space-4xl));
    padding-bottom: var(--space-4xl);
    overflow: hidden;
    background: var(--bg-gradient);
}

.hero-bg {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background:
        radial-gradient(circle at 10% 20%, rgba(99, 102, 241, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 90% 80%, rgba(6, 182, 212, 0.1) 0%, transparent 50%);
    pointer-events: none;
}

.hero-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-3xl);
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-content {
    animation: fadeInUp 0.8s ease;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 8px 18px;
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: var(--border-radius-full);
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--primary);
    margin-bottom: var(--space-lg);
}

.badge-dot {
    width: 8px;
    height: 8px;
    background: var(--success);
    border-radius: 50%;
    animation: pulse 2s infinite;
}

.hero-title {
    font-size: var(--font-size-5xl);
    font-weight: 900;
    line-height: 1.2;
    margin-bottom: var(--space-lg);
    color: var(--text-primary);
}

.title-gradient {
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: var(--space-2xl);
}

.hero-actions {
    display: flex;
    gap: var(--space-md);
    margin-bottom: var(--space-xl);
    flex-wrap: wrap;
}

.hero-meta {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--space-sm);
    font-size: var(--font-size-sm);
    color: var(--text-muted);
    margin-bottom: var(--space-xl);
}

.meta-divider {
    color: var(--gray-400);
}

.hero-hotwords {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--space-sm);
}

.hot-label {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
    font-weight: 500;
}

.hot-tag {
    display: inline-block;
    padding: 4px 14px;
    font-size: var(--font-size-xs);
    color: var(--text-secondary);
    background: var(--white);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-full);
    transition: all var(--transition-fast);
}

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

/* Hero图片 */
.hero-image {
    position: relative;
    display: flex;
    justify-content: center;
    animation: fadeInRight 0.8s ease;
}

.phone-frame {
    position: relative;
    width: 300px;
    border-radius: 40px;
    padding: 12px;
    background: var(--dark);
    box-shadow: var(--shadow-lg);
    transform: rotate(-2deg);
    transition: transform var(--transition-slow);
}

.phone-frame:hover {
    transform: rotate(0deg) scale(1.02);
}

.phone-screen {
    width: 100%;
    border-radius: 30px;
    overflow: hidden;
}

.float-card {
    position: absolute;
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 14px 20px;
    background: var(--white);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    animation: float 3s ease-in-out infinite;
}

.card-1 {
    top: 15%;
    left: -20px;
    animation-delay: 0s;
}

.card-2 {
    bottom: 20%;
    right: -20px;
    animation-delay: 1.5s;
}

.card-icon {
    font-size: 28px;
}

.card-text {
    display: flex;
    flex-direction: column;
}

.card-text strong {
    font-size: var(--font-size-sm);
    font-weight: 700;
    color: var(--text-primary);
}

.card-text span {
    font-size: var(--font-size-xs);
    color: var(--text-muted);
}

/* ========================================
   数据统计
   ======================================== */
.stats {
    padding: var(--space-2xl) 0;
    background: var(--white);
}

.stats-container {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-xl);
}

.stat-item {
    text-align: center;
    padding: var(--space-lg);
}

.stat-number {
    font-size: var(--font-size-5xl);
    font-weight: 900;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1;
    margin-bottom: var(--space-sm);
    display: inline-block;
}

.stat-suffix {
    display: inline-block;
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--primary);
    margin-left: 4px;
}

.stat-label {
    font-size: var(--font-size-base);
    color: var(--text-secondary);
    font-weight: 500;
}

/* ========================================
   功能特色
   ======================================== */
.features {
    background: var(--bg-secondary);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-xl);
}

.feature-card {
    background: var(--white);
    padding: var(--space-2xl);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition);
    border: 1px solid transparent;
    position: relative;
    overflow: hidden;
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--primary-gradient);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--transition);
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-md);
    border-color: rgba(99, 102, 241, 0.1);
}

.feature-card:hover::before {
    transform: scaleX(1);
}

.feature-icon {
    width: 64px;
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 32px;
    background: rgba(99, 102, 241, 0.1);
    border-radius: var(--border-radius);
    margin-bottom: var(--space-lg);
    transition: all var(--transition);
}

.feature-card:hover .feature-icon {
    background: var(--primary-gradient);
    transform: scale(1.1);
}

.feature-title {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--space-sm);
}

.feature-desc {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    line-height: 1.8;
}

/* ========================================
   多场景应用
   ======================================== */
.scenarios {
    background: var(--white);
}

.scenarios-wrapper {
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: var(--space-3xl);
    align-items: center;
}

.scenarios-content {
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
}

.scenario-feature {
    display: flex;
    gap: var(--space-md);
    align-items: flex-start;
    padding: var(--space-md);
    border-radius: var(--border-radius);
    transition: all var(--transition-fast);
}

.scenario-feature:hover {
    background: var(--bg-secondary);
}

.sf-icon {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    background: rgba(99, 102, 241, 0.1);
    border-radius: var(--border-radius);
    transition: all var(--transition);
}

.scenario-feature:hover .sf-icon {
    background: var(--primary-gradient);
}

.sf-text h4 {
    font-size: var(--font-size-lg);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.sf-text p {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    line-height: 1.6;
}

.scenario-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
    margin-top: var(--space-md);
    padding-top: var(--space-lg);
    border-top: 1px solid var(--border-color);
}

.scenario-tag {
    display: inline-block;
    padding: 6px 14px;
    font-size: var(--font-size-xs);
    font-weight: 500;
    color: var(--primary);
    background: rgba(99, 102, 241, 0.08);
    border: 1px solid rgba(99, 102, 241, 0.15);
    border-radius: var(--border-radius-full);
}

.scenarios-visual {
    display: flex;
    justify-content: center;
}

.scenarios-image {
    max-width: 320px;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-lg);
}

/* ========================================
   智能对话体验
   ======================================== */
.chat {
    background: var(--bg-secondary);
}

.chat-wrapper {
    display: grid;
    grid-template-columns: 1fr 1.2fr;
    gap: var(--space-3xl);
    align-items: center;
}

.chat-visual {
    display: flex;
    justify-content: center;
}

.chat-image {
    max-width: 320px;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-lg);
}

.chat-content {
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
}

.chat-feature {
    display: flex;
    gap: var(--space-md);
    align-items: flex-start;
    padding: var(--space-md);
    border-radius: var(--border-radius);
    transition: all var(--transition-fast);
}

.chat-feature:hover {
    background: var(--white);
}

.cf-icon {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    background: var(--primary-gradient);
    border-radius: var(--border-radius);
}

.cf-text h4 {
    font-size: var(--font-size-lg);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.cf-text p {
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    line-height: 1.6;
}

.chat-tips {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
    margin-top: var(--space-md);
    padding-top: var(--space-lg);
    border-top: 1px solid var(--border-color);
}

.chat-tag {
    display: inline-block;
    padding: 6px 14px;
    font-size: var(--font-size-xs);
    font-weight: 500;
    color: var(--primary);
    background: rgba(99, 102, 241, 0.08);
    border: 1px solid rgba(99, 102, 241, 0.15);
    border-radius: var(--border-radius-full);
}

/* ========================================
   更新日志
   ======================================== */
.updates {
    background: var(--white);
}

.update-timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
    padding-left: var(--space-2xl);
}

.update-timeline::before {
    content: '';
    position: absolute;
    left: 8px;
    top: 8px;
    bottom: 8px;
    width: 2px;
    background: linear-gradient(180deg, var(--primary) 0%, var(--accent) 50%, var(--gray-300) 100%);
    border-radius: 2px;
}

.timeline-item {
    position: relative;
    margin-bottom: var(--space-2xl);
}

.timeline-item:last-child {
    margin-bottom: 0;
}

.timeline-dot {
    position: absolute;
    left: calc(-1 * var(--space-2xl) + 1px);
    top: 6px;
    width: 16px;
    height: 16px;
    background: var(--white);
    border: 3px solid var(--primary);
    border-radius: 50%;
    z-index: 1;
}

.timeline-item.latest .timeline-dot {
    background: var(--primary);
    box-shadow: 0 0 0 6px rgba(99, 102, 241, 0.2);
}

.timeline-content {
    background: var(--bg-secondary);
    padding: var(--space-xl);
    border-radius: var(--border-radius);
    transition: all var(--transition);
}

.timeline-item.latest .timeline-content {
    background: var(--white);
    box-shadow: var(--shadow);
    border: 1px solid rgba(99, 102, 241, 0.15);
}

.timeline-header {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    margin-bottom: var(--space-md);
    flex-wrap: wrap;
}

.version-tag {
    display: inline-block;
    padding: 4px 14px;
    font-size: var(--font-size-sm);
    font-weight: 700;
    color: var(--white);
    background: var(--primary-gradient);
    border-radius: var(--border-radius-full);
}

.timeline-date {
    font-size: var(--font-size-sm);
    color: var(--text-muted);
}

.latest-badge {
    display: inline-block;
    padding: 3px 10px;
    font-size: var(--font-size-xs);
    font-weight: 600;
    color: var(--primary);
    background: rgba(99, 102, 241, 0.1);
    border-radius: var(--border-radius-full);
    animation: pulse 2s infinite;
}

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

.update-list li {
    position: relative;
    padding-left: 20px;
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 4px;
}

.update-list li::before {
    content: '•';
    position: absolute;
    left: 6px;
    color: var(--primary);
    font-weight: 700;
}

.update-list li strong {
    color: var(--text-primary);
    font-weight: 600;
}

/* ========================================
   下载CTA
   ======================================== */
.download-cta {
    position: relative;
    padding: var(--space-4xl) 0;
    background: var(--primary-gradient-vertical);
    overflow: hidden;
}

.download-cta::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -10%;
    width: 400px;
    height: 400px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 50%;
}

.download-cta::after {
    content: '';
    position: absolute;
    bottom: -30%;
    left: -5%;
    width: 300px;
    height: 300px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 50%;
}

.cta-content {
    position: relative;
    z-index: 1;
    text-align: center;
    color: var(--white);
}

.cta-title {
    font-size: var(--font-size-4xl);
    font-weight: 800;
    margin-bottom: var(--space-md);
}

.cta-desc {
    font-size: var(--font-size-lg);
    opacity: 0.9;
    margin-bottom: var(--space-2xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.download-cta .btn-primary {
    background: var(--white);
    color: var(--primary);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.2);
}

.download-cta .btn-primary:hover {
    color: var(--primary);
    transform: translateY(-3px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.25);
}

.cta-note {
    margin-top: var(--space-lg);
    font-size: var(--font-size-sm);
    opacity: 0.8;
}

/* ========================================
   常见问题
   ======================================== */
.faq {
    background: var(--white);
}

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

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

.faq-item:hover {
    border-color: rgba(99, 102, 241, 0.3);
}

.faq-item.active {
    border-color: var(--primary);
    box-shadow: var(--shadow-sm);
}

.faq-question {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-md);
    padding: var(--space-lg) var(--space-xl);
    font-size: var(--font-size-base);
    font-weight: 600;
    color: var(--text-primary);
    text-align: left;
    background: var(--white);
    transition: all var(--transition-fast);
}

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

.faq-icon {
    flex-shrink: 0;
    width: 28px;
    height: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    font-weight: 400;
    color: var(--primary);
    background: rgba(99, 102, 241, 0.1);
    border-radius: 50%;
    transition: transform var(--transition);
}

.faq-item.active .faq-icon {
    transform: rotate(45deg);
    background: var(--primary);
    color: var(--white);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-slow), padding var(--transition);
}

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

.faq-answer p {
    padding: 0 var(--space-xl) var(--space-lg);
    font-size: var(--font-size-sm);
    color: var(--text-secondary);
    line-height: 1.8;
}

/* ========================================
   页脚
   ======================================== */
.footer {
    background: var(--dark);
    color: var(--gray-400);
    padding: var(--space-3xl) 0 var(--space-xl);
}

.footer-top {
    display: grid;
    grid-template-columns: 1.5fr 2fr;
    gap: var(--space-3xl);
    margin-bottom: var(--space-2xl);
}

.footer-brand {
    max-width: 360px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 800;
    font-size: var(--font-size-xl);
    color: var(--white);
    margin-bottom: var(--space-md);
}

.footer-logo:hover {
    color: var(--white);
}

.footer-logo .logo-text {
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.footer-desc {
    font-size: var(--font-size-sm);
    line-height: 1.8;
    color: var(--gray-500);
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-xl);
}

.footer-col h4 {
    font-size: var(--font-size-base);
    font-weight: 700;
    color: var(--white);
    margin-bottom: var(--space-lg);
}

.footer-col a {
    display: block;
    font-size: var(--font-size-sm);
    color: var(--gray-500);
    margin-bottom: var(--space-sm);
    transition: color var(--transition-fast);
}

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

.footer-download {
    display: inline-flex !important;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    background: var(--primary-gradient);
    color: var(--white) !important;
    border-radius: var(--border-radius-full);
    font-weight: 600;
    margin-bottom: var(--space-md) !important;
}

.footer-download:hover {
    color: var(--white) !important;
    transform: translateY(-2px);
    box-shadow: var(--shadow-primary);
}

.dl-icon {
    font-weight: 700;
}

.footer-version {
    font-size: var(--font-size-xs);
    color: var(--gray-600);
    line-height: 1.6;
}

.footer-bottom {
    padding-top: var(--space-xl);
    border-top: 1px solid rgba(255, 255, 255, 0.08);
    text-align: center;
}

.footer-bottom p {
    font-size: var(--font-size-sm);
    color: var(--gray-600);
    margin-bottom: 6px;
}

.footer-disclaimer {
    font-size: var(--font-size-xs) !important;
    color: var(--gray-700) !important;
}

/* ========================================
   回到顶部
   ======================================== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 22px;
    font-weight: 700;
    color: var(--white);
    background: var(--primary-gradient);
    border-radius: 50%;
    box-shadow: var(--shadow-primary);
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all var(--transition);
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-primary-lg);
}

/* ========================================
   动画
   ======================================== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

@keyframes float {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-12px);
    }
}

@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.6;
    }
}

/* 滚动动画 */
.scroll-reveal {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.scroll-reveal.revealed {
    opacity: 1;
    transform: translateY(0);
}

/* ========================================
   响应式适配
   ======================================== */

/* 大屏桌面 */
@media (max-width: 1200px) {
    :root {
        --container-max: 100%;
    }
}

/* 平板横屏 */
@media (max-width: 1024px) {
    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-content {
        order: 1;
    }

    .hero-image {
        order: 0;
        margin-bottom: var(--space-2xl);
    }

    .hero-actions,
    .hero-meta,
    .hero-hotwords {
        justify-content: center;
    }

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

    .scenarios-wrapper,
    .chat-wrapper {
        grid-template-columns: 1fr;
    }

    .scenarios-visual,
    .chat-visual {
        order: -1;
    }

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

    .footer-brand {
        max-width: 100%;
        text-align: center;
    }

    .footer-logo {
        justify-content: center;
    }
}

/* 平板竖屏 */
@media (max-width: 768px) {
    :root {
        --navbar-height: 60px;
        --space-4xl: 56px;
        --space-3xl: 40px;
    }

    section {
        padding: var(--space-3xl) 0;
    }

    .section-title {
        font-size: var(--font-size-3xl);
    }

    .section-desc {
        font-size: var(--font-size-base);
    }

    /* 导航栏移动端 */
    .nav-menu {
        position: fixed;
        top: var(--navbar-height);
        left: 0;
        right: 0;
        flex-direction: column;
        gap: 0;
        background: var(--white);
        box-shadow: var(--shadow-md);
        padding: var(--space-md) 0;
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition);
    }

    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-link {
        display: block;
        padding: var(--space-md) var(--container-padding);
        width: 100%;
        text-align: center;
    }

    .nav-link::after {
        display: none;
    }

    .nav-download {
        display: none;
    }

    .nav-toggle {
        display: flex;
    }

    /* Hero */
    .hero {
        padding-top: calc(var(--navbar-height) + var(--space-2xl));
    }

    .hero-title {
        font-size: var(--font-size-4xl);
    }

    .hero-subtitle {
        font-size: var(--font-size-base);
    }

    .phone-frame {
        width: 240px;
    }

    .float-card {
        display: none;
    }

    /* 统计 */
    .stats-container {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-lg);
    }

    .stat-number {
        font-size: var(--font-size-4xl);
    }

    /* 功能 */
    .features-grid {
        grid-template-columns: 1fr;
    }

    /* 页脚 */
    .footer-links {
        grid-template-columns: repeat(2, 1fr);
    }

    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 44px;
        height: 44px;
        font-size: 18px;
    }
}

/* 手机 */
@media (max-width: 480px) {
    :root {
        --container-padding: 16px;
    }

    .section-title {
        font-size: var(--font-size-2xl);
    }

    .hero-title {
        font-size: var(--font-size-3xl);
    }

    .hero-actions {
        flex-direction: column;
        width: 100%;
    }

    .hero-actions .btn {
        width: 100%;
    }

    .btn-xl {
        padding: 16px 32px;
        font-size: var(--font-size-lg);
    }

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

    .footer-links {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .footer-col a {
        text-align: center;
    }

    .scenario-feature,
    .chat-feature {
        flex-direction: column;
        gap: var(--space-sm);
    }

    .timeline-header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--space-sm);
    }
}

/* 减少动画偏好 */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}