/* ===== 基础变量与重置 ===== */
:root {
    --primary: #6366f1;
    --primary-light: #818cf8;
    --primary-dark: #4f46e5;
    --secondary: #06b6d4;
    --accent: #f59e0b;
    --bg: #0f0f1a;
    --bg-light: #16162a;
    --bg-card: #1e1e3a;
    --bg-card-hover: #252550;
    --text: #f1f5f9;
    --text-muted: #94a3b8;
    --text-dim: #64748b;
    --border: rgba(255,255,255,0.08);
    --shadow: 0 8px 32px rgba(0,0,0,0.4);
    --shadow-lg: 0 20px 60px rgba(0,0,0,0.5);
    --radius: 16px;
    --radius-lg: 24px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

a {
    text-decoration: none;
    color: inherit;
}

ul, ol {
    list-style: none;
}

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

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== 导航栏 ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 16px 0;
    transition: var(--transition);
    background: transparent;
}

.navbar.scrolled {
    background: rgba(15, 15, 26, 0.85);
    backdrop-filter: blur(20px) saturate(1.5);
    -webkit-backdrop-filter: blur(20px) saturate(1.5);
    border-bottom: 1px solid var(--border);
    padding: 12px 0;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--text);
}

.logo-icon {
    width: 36px;
    height: 36px;
    color: var(--primary-light);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
    z-index: 1001;
}

.nav-toggle span {
    display: block;
    width: 24px;
    height: 2.5px;
    background: var(--text);
    border-radius: 2px;
    transition: var(--transition);
}

.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);
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-link {
    padding: 8px 16px;
    border-radius: 10px;
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--text-muted);
    transition: var(--transition);
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--text);
    background: rgba(99, 102, 241, 0.12);
}

/* ===== 英雄区 ===== */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 120px 24px 80px;
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    inset: 0;
    z-index: 0;
    overflow: hidden;
}

.gradient-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.5;
    animation: float 8s ease-in-out infinite;
}

.orb-1 {
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, var(--primary), transparent 70%);
    top: -10%;
    left: -10%;
    animation-delay: 0s;
}

.orb-2 {
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, var(--secondary), transparent 70%);
    bottom: -10%;
    right: -5%;
    animation-delay: -3s;
}

.orb-3 {
    width: 300px;
    height: 300px;
    background: radial-gradient(circle, var(--accent), transparent 70%);
    top: 40%;
    left: 50%;
    animation-delay: -5s;
    opacity: 0.3;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) scale(1); }
    33% { transform: translate(30px, -30px) scale(1.05); }
    66% { transform: translate(-20px, 20px) scale(0.95); }
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    max-width: 720px;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 6px 16px;
    background: rgba(99, 102, 241, 0.15);
    border: 1px solid rgba(99, 102, 241, 0.3);
    border-radius: 100px;
    font-size: 0.875rem;
    color: var(--primary-light);
    margin-bottom: 28px;
    animation: fadeInUp 0.6s ease-out;
}

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

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.4; }
}

.hero-title {
    font-size: clamp(2.2rem, 6vw, 4rem);
    font-weight: 900;
    line-height: 1.15;
    margin-bottom: 20px;
    animation: fadeInUp 0.6s ease-out 0.1s both;
}

.gradient-text {
    background: linear-gradient(135deg, var(--primary-light), var(--secondary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: clamp(1rem, 2.5vw, 1.25rem);
    color: var(--text-muted);
    max-width: 560px;
    margin: 0 auto 36px;
    animation: fadeInUp 0.6s ease-out 0.2s both;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 56px;
    animation: fadeInUp 0.6s ease-out 0.3s both;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 32px;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 600;
    transition: var(--transition);
    cursor: pointer;
    border: none;
    white-space: nowrap;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    box-shadow: 0 4px 20px rgba(99, 102, 241, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(99, 102, 241, 0.5);
}

.btn-secondary {
    background: rgba(255,255,255,0.06);
    color: var(--text);
    border: 1px solid var(--border);
}

.btn-secondary:hover {
    background: rgba(255,255,255,0.1);
    border-color: rgba(255,255,255,0.15);
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 48px;
    flex-wrap: wrap;
    animation: fadeInUp 0.6s ease-out 0.4s both;
}

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

.stat-number {
    display: block;
    font-size: 2rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary-light), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: 0.875rem;
    color: var(--text-dim);
}

/* 设备模拟器 */
.hero-visual {
    position: absolute;
    right: 5%;
    top: 50%;
    transform: translateY(-50%);
    z-index: 1;
    opacity: 0.15;
    pointer-events: none;
}

.device-mockup {
    width: 300px;
    background: var(--bg-card);
    border-radius: 20px;
    padding: 12px;
    border: 1px solid var(--border);
    box-shadow: var(--shadow-lg);
    animation: fadeInUp 0.8s ease-out 0.5s both;
}

.mockup-screen {
    background: var(--bg);
    border-radius: 12px;
    overflow: hidden;
}

.screen-header {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 14px;
    background: rgba(255,255,255,0.03);
    border-bottom: 1px solid var(--border);
}

.screen-dots {
    display: flex;
    gap: 6px;
}

.screen-dots span {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--text-dim);
}

.screen-dots span:first-child { background: #ef4444; }
.screen-dots span:nth-child(2) { background: #f59e0b; }
.screen-dots span:last-child { background: #22c55e; }

.screen-title {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-weight: 500;
}

.screen-content {
    padding: 24px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
}

.progress-ring {
    position: relative;
    width: 100px;
    height: 100px;
}

.progress-ring svg {
    transform: rotate(-90deg);
    width: 100%;
    height: 100%;
}

.progress-bg {
    fill: none;
    stroke: rgba(255,255,255,0.06);
    stroke-width: 6;
}

.progress-bar {
    fill: none;
    stroke: url(#progressGradient);
    stroke-width: 6;
    stroke-linecap: round;
    stroke-dasharray: 264;
    stroke-dashoffset: 5;
    animation: progressAnim 2s ease-out forwards;
}

.progress-text {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--primary-light);
}

.screen-info {
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.info-row {
    display: flex;
    justify-content: space-between;
    font-size: 0.8125rem;
    color: var(--text-muted);
}

.info-row span:last-child {
    color: var(--text);
    font-weight: 500;
}

.status-success {
    color: #22c55e !important;
}

.scroll-indicator {
    position: absolute;
    bottom: 32px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    color: var(--text-dim);
    font-size: 0.75rem;
    animation: fadeInUp 0.6s ease-out 0.8s both;
}

.mouse {
    width: 22px;
    height: 34px;
    border: 2px solid var(--text-dim);
    border-radius: 12px;
    display: flex;
    justify-content: center;
    padding-top: 6px;
}

.wheel {
    width: 3px;
    height: 6px;
    background: var(--text-dim);
    border-radius: 2px;
    animation: scrollWheel 2s infinite;
}

@keyframes scrollWheel {
    0% { transform: translateY(0); opacity: 1; }
    100% { transform: translateY(8px); opacity: 0; }
}

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

/* ===== 通用区块 ===== */
section {
    padding: 100px 0;
    position: relative;
}

.section-header {
    text-align: center;
    max-width: 600px;
    margin: 0 auto 64px;
}

.section-tag {
    display: inline-block;
    padding: 6px 16px;
    background: rgba(99, 102, 241, 0.12);
    border: 1px solid rgba(99, 102, 241, 0.25);
    border-radius: 100px;
    font-size: 0.8125rem;
    font-weight: 600;
    color: var(--primary-light);
    margin-bottom: 16px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.section-title {
    font-size: clamp(1.75rem, 4vw, 2.75rem);
    font-weight: 800;
    margin-bottom: 16px;
    line-height: 1.2;
}

.section-desc {
    font-size: 1.0625rem;
    color: var(--text-muted);
}

/* ===== 功能优势 ===== */
.features {
    background: linear-gradient(180deg, var(--bg) 0%, var(--bg-light) 100%);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
}

.feature-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 36px 28px;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    opacity: 0;
    transition: var(--transition);
}

.feature-card:hover {
    transform: translateY(-4px);
    background: var(--bg-card-hover);
    border-color: rgba(99, 102, 241, 0.2);
    box-shadow: var(--shadow-lg);
}

.feature-card:hover::before {
    opacity: 1;
}

.feature-icon {
    width: 56px;
    height: 56px;
    background: linear-gradient(135deg, rgba(99,102,241,0.15), rgba(6,182,212,0.15));
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
    color: var(--primary-light);
}

.feature-icon svg {
    width: 28px;
    height: 28px;
}

.feature-card h3 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 10px;
}

.feature-card p {
    color: var(--text-muted);
    font-size: 0.9375rem;
    line-height: 1.7;
}

/* ===== 使用场景 ===== */
.scenes-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
}

.scene-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: var(--transition);
}

.scene-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(99, 102, 241, 0.2);
}

.scene-image {
    padding: 32px;
    display: flex;
    justify-content: center;
    background: linear-gradient(135deg, rgba(99,102,241,0.08), rgba(6,182,212,0.08));
}

.scene-icon-bg {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    box-shadow: 0 8px 24px rgba(99, 102, 241, 0.3);
}

.scene-icon-bg.bg-2 {
    background: linear-gradient(135deg, #ec4899, #f59e0b);
    box-shadow: 0 8px 24px rgba(236, 72, 153, 0.3);
}

.scene-icon-bg.bg-3 {
    background: linear-gradient(135deg, #22c55e, #06b6d4);
    box-shadow: 0 8px 24px rgba(34, 197, 94, 0.3);
}

.scene-icon-bg.bg-4 {
    background: linear-gradient(135deg, #8b5cf6, #ec4899);
    box-shadow: 0 8px 24px rgba(139, 92, 246, 0.3);
}

.scene-icon-bg svg {
    width: 40px;
    height: 40px;
}

.scene-content {
    padding: 24px 28px 28px;
}

.scene-content h3 {
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 10px;
}

.scene-content p {
    color: var(--text-muted);
    font-size: 0.9375rem;
    margin-bottom: 16px;
    line-height: 1.7;
}

.scene-tags {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.scene-tags span {
    padding: 4px 12px;
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: 6px;
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--primary-light);
}

/* ===== 下载区 ===== */
.download {
    padding: 60px 0 100px;
}

.download-card {
    background: linear-gradient(135deg, rgba(99,102,241,0.15), rgba(6,182,212,0.1));
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: var(--radius-lg);
    padding: 60px 40px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.download-card::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(99,102,241,0.08) 0%, transparent 60%);
    pointer-events: none;
}

.download-content {
    position: relative;
    z-index: 1;
}

.download-content h2 {
    font-size: clamp(1.5rem, 4vw, 2.25rem);
    font-weight: 800;
    margin-bottom: 8px;
}

.download-content > p {
    color: var(--text-muted);
    margin-bottom: 32px;
    font-size: 1.0625rem;
}

.download-buttons {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 28px;
}

.btn-download {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    padding: 16px 36px;
    font-size: 1.0625rem;
    box-shadow: 0 4px 20px rgba(99, 102, 241, 0.4);
}

.btn-download:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(99, 102, 241, 0.5);
}

.btn-download-outline {
    background: rgba(255,255,255,0.05);
    color: var(--text);
    border: 1px solid rgba(255,255,255,0.15);
    padding: 16px 36px;
    font-size: 1.0625rem;
}

.btn-download-outline:hover {
    background: rgba(255,255,255,0.1);
    border-color: rgba(255,255,255,0.25);
}

.download-meta {
    display: flex;
    gap: 12px;
    justify-content: center;
    flex-wrap: wrap;
    font-size: 0.875rem;
    color: var(--text-dim);
}

.divider {
    color: var(--text-dim);
    opacity: 0.4;
}

/* ===== 法律文本区 ===== */
.legal {
    padding: 80px 0;
}

.legal:nth-of-type(odd) {
    background: var(--bg-light);
}

.legal-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    overflow: hidden;
}

.legal-header {
    padding: 40px 40px 0;
    text-align: center;
}

.legal-icon {
    width: 64px;
    height: 64px;
    background: linear-gradient(135deg, rgba(99,102,241,0.15), rgba(6,182,212,0.15));
    border-radius: 18px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    color: var(--primary-light);
}

.legal-icon svg {
    width: 32px;
    height: 32px;
}

.legal-header h2 {
    font-size: clamp(1.5rem, 4vw, 2rem);
    font-weight: 800;
    margin-bottom: 8px;
}

.legal-date {
    display: inline-block;
    padding: 4px 14px;
    background: rgba(99, 102, 241, 0.1);
    border-radius: 6px;
    font-size: 0.8125rem;
    color: var(--text-muted);
}

.legal-body {
    padding: 40px;
}

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

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

.legal-section h3 {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--primary-light);
    margin-bottom: 14px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--border);
}

.legal-section h4 {
    font-size: 1rem;
    font-weight: 600;
    margin: 18px 0 10px;
    color: var(--text);
}

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

.legal-section ul {
    margin: 12px 0;
    padding-left: 20px;
}

.legal-section ul li {
    color: var(--text-muted);
    margin-bottom: 8px;
    line-height: 1.7;
    position: relative;
    padding-left: 16px;
}

.legal-section ul li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 10px;
    width: 6px;
    height: 6px;
    background: var(--primary);
    border-radius: 50%;
}

.legal-section strong {
    color: var(--text);
    font-weight: 600;
}

.table-wrapper {
    overflow-x: auto;
    margin: 16px 0;
    border-radius: 12px;
    border: 1px solid var(--border);
}

.legal-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.875rem;
    min-width: 500px;
}

.legal-table thead {
    background: rgba(99, 102, 241, 0.1);
}

.legal-table th {
    padding: 14px 16px;
    text-align: left;
    font-weight: 600;
    color: var(--text);
    border-bottom: 1px solid var(--border);
}

.legal-table td {
    padding: 12px 16px;
    color: var(--text-muted);
    border-bottom: 1px solid var(--border);
}

.legal-table tbody tr:last-child td {
    border-bottom: none;
}

.legal-table tbody tr:hover {
    background: rgba(255,255,255,0.02);
}

.legal-footer-text {
    text-align: center;
    color: var(--text-dim) !important;
    font-style: italic;
    margin-top: 24px;
    padding-top: 24px;
    border-top: 1px solid var(--border);
}

/* ===== 联系我们 ===== */
.contact {
    background: linear-gradient(180deg, var(--bg-light) 0%, var(--bg) 100%);
    padding-bottom: 60px;
}

.contact-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 24px;
}

.contact-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 36px 28px;
    text-align: center;
    transition: var(--transition);
}

.contact-card:hover {
    transform: translateY(-4px);
    border-color: rgba(99, 102, 241, 0.3);
    box-shadow: var(--shadow-lg);
}

.contact-icon {
    width: 56px;
    height: 56px;
    background: linear-gradient(135deg, rgba(99,102,241,0.15), rgba(6,182,212,0.15));
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 18px;
    color: var(--primary-light);
}

.contact-icon svg {
    width: 26px;
    height: 26px;
}

.contact-card h3 {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 6px;
}

.contact-card > p {
    color: var(--text-muted);
    font-size: 0.9375rem;
    margin-bottom: 12px;
    word-break: break-all;
}

.contact-link {
    display: inline-block;
    padding: 8px 20px;
    background: rgba(99, 102, 241, 0.12);
    border: 1px solid rgba(99, 102, 241, 0.25);
    border-radius: 8px;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--primary-light);
    transition: var(--transition);
}

.contact-link:hover {
    background: rgba(99, 102, 241, 0.2);
}

.contact-note {
    font-size: 0.8125rem;
    color: var(--text-dim);
}

/* ===== 页脚 ===== */
.footer {
    background: var(--bg);
    border-top: 1px solid var(--border);
    padding: 60px 0 24px;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    flex-wrap: wrap;
    gap: 40px;
    margin-bottom: 40px;
}

.footer-brand .logo {
    margin-bottom: 12px;
}

.footer-brand p {
    color: var(--text-dim);
    font-size: 0.9375rem;
}

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

.footer-col h4 {
    font-size: 0.9375rem;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--text);
}

.footer-col a {
    display: block;
    color: var(--text-muted);
    font-size: 0.875rem;
    margin-bottom: 10px;
    transition: var(--transition);
}

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

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

.footer-bottom p {
    color: var(--text-dim);
    font-size: 0.8125rem;
    margin-bottom: 6px;
}

.footer-contact {
    color: var(--text-muted) !important;
}

/* ===== 回到顶部 ===== */
.back-to-top {
    position: fixed;
    bottom: 24px;
    right: 24px;
    width: 48px;
    height: 48px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: var(--transition);
    z-index: 999;
}

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

.back-to-top:hover {
    background: var(--primary);
    border-color: var(--primary);
    color: white;
    transform: translateY(-2px);
}

.back-to-top svg {
    width: 20px;
    height: 20px;
}

/* ===== 响应式 ===== */
@media (max-width: 1024px) {
    .hero-visual {
        display: none;
    }
}

@media (max-width: 768px) {
    .nav-toggle {
        display: flex;
    }

    .nav-menu {
        position: fixed;
        top: 0;
        right: -100%;
        width: 75%;
        max-width: 300px;
        height: 100vh;
        background: var(--bg-card);
        flex-direction: column;
        align-items: flex-start;
        padding: 80px 24px 24px;
        gap: 4px;
        transition: right 0.3s ease;
        border-left: 1px solid var(--border);
        z-index: 1000;
    }

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

    .nav-link {
        width: 100%;
        padding: 12px 16px;
    }

    .hero {
        padding: 100px 20px 60px;
        min-height: auto;
    }

    .hero-stats {
        gap: 32px;
    }

    section {
        padding: 60px 0;
    }

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

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

    .legal-header,
    .legal-body {
        padding: 28px 20px;
    }

    .download-card {
        padding: 40px 24px;
    }

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

    .btn-download,
    .btn-download-outline {
        width: 100%;
        max-width: 280px;
        justify-content: center;
    }

    .footer-content {
        flex-direction: column;
        align-items: center;
        text-align: center;
    }

    .footer-links {
        justify-content: center;
        gap: 40px;
    }

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

@media (max-width: 480px) {
    html {
        font-size: 15px;
    }

    .container {
        padding: 0 16px;
    }

    .hero-title {
        font-size: 2rem;
    }

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

    .btn {
        width: 100%;
        max-width: 260px;
        justify-content: center;
    }

    .stat-number {
        font-size: 1.5rem;
    }

    .feature-card {
        padding: 28px 20px;
    }

    .legal-table {
        font-size: 0.8125rem;
    }

    .legal-table th,
    .legal-table td {
        padding: 10px 12px;
    }
}

/* 平板横屏与折叠屏优化 */
@media (min-width: 769px) and (max-width: 1024px) {
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }

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

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

/* 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;
    }

    html {
        scroll-behavior: auto;
    }
}