:root {
    --blue: #1677FF;
    --blue-dark: #0958D9;
    --blue-light: #E8F4FD;
    --text: #1D2129;
    --text-secondary: #4E5969;
    --text-muted: #86909C;
    --bg: #FFFFFF;
    --bg-secondary: #F7F8FA;
    --border: #E5E6EB;
    --border-light: #F2F3F5;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
    --shadow: 0 2px 8px rgba(0,0,0,0.06);
    --shadow-lg: 0 4px 20px rgba(0,0,0,0.08);
    --shadow-xl: 0 8px 40px rgba(0,0,0,0.12);
}

*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
    font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
    color: var(--text);
    background: var(--bg);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ========== NAVIGATION ========== */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    height: 64px;
    background: rgba(255,255,255,0.85);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    transition: box-shadow 0.3s, border-color 0.3s;
    border-bottom: 1px solid transparent;
}
.nav.scrolled {
    border-bottom-color: var(--border);
    box-shadow: var(--shadow-sm);
}
.nav-inner {
    max-width: 1280px;
    height: 100%;
    margin: 0 auto;
    padding: 0 40px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}
.nav-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
}
.nav-brand img { width: 36px; height: 36px; }
.nav-brand span {
    font-size: 20px;
    font-weight: 700;
    color: var(--text);
    letter-spacing: -0.3px;
}
.nav-links {
    display: flex;
    align-items: center;
    gap: 32px;
    list-style: none;
}
.nav-links a {
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 15px;
    font-weight: 500;
    transition: color 0.2s;
}
.nav-links a:hover { color: var(--blue); }
.nav-btn {
    background: var(--blue);
    color: #fff;
    text-decoration: none;
    padding: 9px 24px;
    border-radius: 24px;
    font-size: 14px;
    font-weight: 600;
    transition: all 0.2s;
    white-space: nowrap;
}
.nav-btn:hover {
    background: var(--blue-dark);
    box-shadow: 0 4px 12px rgba(22,119,255,0.3);
    transform: translateY(-1px);
}

/* ========== HERO ========== */
.hero {
    padding: 160px 40px 120px;
    position: relative;
    background: linear-gradient(180deg, #F0F6FF 0%, #FAFBFC 40%, #FFFFFF 100%);
    overflow: hidden;
}
.hero::before {
    content: '';
    position: absolute;
    top: -40%;
    right: -15%;
    width: 900px;
    height: 900px;
    background: radial-gradient(circle, rgba(22,119,255,0.05) 0%, transparent 60%);
    border-radius: 50%;
    pointer-events: none;
}
.hero-grid {
    max-width: 1280px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1.2fr;
    gap: 80px;
    align-items: center;
    position: relative;
    z-index: 1;
}
.hero-text { max-width: 520px; }
.hero-text .tag {
    display: inline-block;
    padding: 5px 16px;
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 20px;
    font-size: 13px;
    font-weight: 600;
    color: var(--blue);
    margin-bottom: 28px;
}
.hero h1 {
    font-size: 56px;
    font-weight: 800;
    line-height: 1.15;
    letter-spacing: -2px;
    color: var(--text);
    margin-bottom: 24px;
}
.hero h1 em {
    font-style: normal;
    color: var(--blue);
}
.hero-desc {
    font-size: 17px;
    color: var(--text-secondary);
    line-height: 1.75;
    margin-bottom: 40px;
}
.hero-actions {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
    align-items: center;
}
.hero-image {
    background: #fff;
    border-radius: 24px;
    box-shadow: var(--shadow-xl);
    overflow: hidden;
    border: 1px solid var(--border);
    aspect-ratio: 16 / 10;
}
.hero-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

/* ========== BUTTONS ========== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 14px 36px;
    font-size: 16px;
    font-weight: 600;
    border-radius: 28px;
    text-decoration: none;
    transition: all 0.25s;
    border: none;
    cursor: pointer;
    white-space: nowrap;
}
.btn-primary {
    background: var(--blue);
    color: #fff;
    box-shadow: 0 4px 16px rgba(22,119,255,0.3);
}
.btn-primary:hover {
    background: var(--blue-dark);
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(22,119,255,0.4);
}
.btn-secondary {
    background: #fff;
    color: var(--text);
    border: 1px solid var(--border);
}
.btn-secondary:hover {
    border-color: #C9CDD4;
    background: var(--bg-secondary);
}

/* ========== SECTIONS ========== */
.section {
    padding: 100px 40px;
}
.section-inner {
    max-width: 1280px;
    margin: 0 auto;
}
.section-header {
    text-align: center;
    margin-bottom: 64px;
}
.section-header h2 {
    font-size: 38px;
    font-weight: 700;
    letter-spacing: -1px;
    color: var(--text);
    margin-bottom: 16px;
}
.section-header p {
    font-size: 16px;
    color: var(--text-muted);
    max-width: 520px;
    margin: 0 auto;
    line-height: 1.7;
}

/* ========== FEATURES ========== */
.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}
.feature-card {
    background: var(--bg-secondary);
    border-radius: 16px;
    padding: 40px 36px;
    transition: all 0.3s;
    border: 1px solid transparent;
}
.feature-card:hover {
    background: #fff;
    border-color: var(--border);
    box-shadow: var(--shadow-lg);
}
.feature-card h4 {
    font-size: 18px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 10px;
}
.feature-card p {
    font-size: 14px;
    color: var(--text-muted);
    line-height: 1.7;
}

/* ========== STATS ========== */
.stats-section {
    background: var(--text);
    padding: 64px 40px;
}
.stats-row {
    max-width: 1280px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 40px;
    text-align: center;
}
.stat-num {
    font-size: 44px;
    font-weight: 800;
    color: #fff;
    letter-spacing: -2px;
    line-height: 1;
    margin-bottom: 8px;
}
.stat-num .unit {
    font-size: 20px;
    font-weight: 500;
    color: rgba(255,255,255,0.5);
}
.stat-label {
    font-size: 14px;
    color: rgba(255,255,255,0.45);
    font-weight: 500;
}

/* ========== AI PRODUCTS ========== */
.bg-gray { background: var(--bg-secondary); }
.products-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}
.product-card {
    background: #fff;
    border-radius: 16px;
    padding: 40px 28px 32px;
    text-align: center;
    text-decoration: none;
    color: inherit;
    transition: all 0.3s;
    border: 1px solid transparent;
    display: block;
}
.product-card:hover {
    border-color: var(--border);
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}
.product-card img {
    width: 64px;
    height: 64px;
    margin-bottom: 20px;
    object-fit: contain;
}
.product-card h5 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text);
}
.product-card p {
    font-size: 13px;
    color: var(--text-muted);
    line-height: 1.6;
}

/* ========== DOWNLOAD ========== */
.download-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}
.download-card {
    background: var(--bg-secondary);
    border-radius: 16px;
    padding: 36px 28px 28px;
    text-align: center;
    transition: all 0.3s;
    border: 1px solid transparent;
}
.download-card:hover {
    background: #fff;
    border-color: var(--border);
    box-shadow: var(--shadow-lg);
}
.download-card h4 {
    font-size: 20px;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 6px;
}
.download-card .platform {
    font-size: 13px;
    color: var(--text-muted);
    margin-bottom: 24px;
}
.dl-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 32px;
    background: var(--blue);
    color: #fff;
    border-radius: 24px;
    font-size: 14px;
    font-weight: 600;
    text-decoration: none;
    transition: all 0.2s;
}
.dl-btn:hover {
    background: var(--blue-dark);
    box-shadow: 0 4px 12px rgba(22,119,255,0.3);
}

/* ========== FAQ ========== */
.faq-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
}
.faq-item {
    background: #fff;
    border: 1px solid var(--border-light);
    border-radius: 12px;
    padding: 28px;
    transition: all 0.25s;
}
.faq-item:hover {
    border-color: var(--border);
    box-shadow: var(--shadow);
}
.faq-item h5 {
    font-size: 15px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 10px;
}
.faq-item p {
    font-size: 14px;
    color: var(--text-muted);
    line-height: 1.7;
}

/* ========== CTA ========== */
.cta {
    padding: 100px 40px;
    text-align: center;
    background: linear-gradient(180deg, var(--blue-light) 0%, #fff 100%);
}
.cta h2 {
    font-size: 36px;
    font-weight: 700;
    letter-spacing: -1px;
    color: var(--text);
    margin-bottom: 14px;
}
.cta p {
    font-size: 16px;
    color: var(--text-muted);
    margin-bottom: 36px;
}

/* ========== FOOTER ========== */
.footer {
    background: #0F172A;
    padding: 64px 40px 36px;
}
.footer-inner {
    max-width: 1280px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 48px;
}
.footer-brand {
    color: #fff;
    font-size: 18px;
    font-weight: 700;
    margin-bottom: 10px;
}
.footer-tagline {
    font-size: 13px;
    color: #64748B;
    margin-bottom: 6px;
}
.footer-copyright {
    font-size: 12px;
    color: #475569;
}
.footer-col h6 {
    font-size: 12px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: #94A3B8;
    margin-bottom: 20px;
}
.footer-col a {
    display: block;
    color: #64748B;
    text-decoration: none;
    font-size: 14px;
    margin-bottom: 12px;
    transition: color 0.2s;
}
.footer-col a:hover { color: #E2E8F0; }
.footer-bottom {
    max-width: 1280px;
    margin: 48px auto 0;
    padding-top: 28px;
    border-top: 1px solid rgba(148,163,184,0.1);
    font-size: 13px;
    color: #475569;
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 12px;
}
.footer-bottom a {
    color: #64748B;
    text-decoration: none;
}
.footer-bottom a:hover { color: #E2E8F0; }

/* ========== RESPONSIVE ========== */
@media (max-width: 1100px) {
    .hero-grid { grid-template-columns: 1fr; gap: 48px; }
    .hero-image { max-width: 560px; margin: 0 auto; }
    .hero-text { max-width: 600px; }
    .hero h1 { font-size: 42px; }
    .features-grid { grid-template-columns: repeat(2, 1fr); }
    .products-grid { grid-template-columns: repeat(2, 1fr); }
    .download-grid { grid-template-columns: repeat(2, 1fr); }
    .stats-row { grid-template-columns: repeat(2, 1fr); gap: 32px; }
    .footer-inner { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
    .nav-links { display: none; }
    .hero { padding: 120px 20px 80px; }
    .hero h1 { font-size: 32px; }
    .section { padding: 64px 20px; }
    .section-header h2 { font-size: 28px; }
    .features-grid { grid-template-columns: 1fr; }
    .products-grid { grid-template-columns: 1fr; }
    .download-grid { grid-template-columns: 1fr; }
    .faq-grid { grid-template-columns: 1fr; }
    .hero-actions { flex-direction: column; }
    .hero-actions .btn { width: 100%; }
    .stats-row { grid-template-columns: repeat(2, 1fr); }
    .stat-num { font-size: 32px; }
    .footer-inner { grid-template-columns: 1fr 1fr; }
}