/* ========== Reset & Base ========== */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary: #4D8CF5;
    --primary-dark: #2B6ED9;
    --primary-light: #E8F0FE;
    --red: #D4382C;
    --green: #34A853;
    --orange: #FF6D01;
    --text: #1a1a2e;
    --text-secondary: #555;
    --text-light: #888;
    --bg: #ffffff;
    --bg-gray: #f7f8fa;
    --bg-dark: #1a1a2e;
    --border: #e5e7eb;
    --shadow: 0 2px 16px rgba(0,0,0,0.06);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.10);
    --radius: 12px;
    --radius-lg: 20px;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
    color: var(--text);
    background: var(--bg);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
}

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

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

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

/* ========== Header ========== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255,255,255,0.92);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    transition: box-shadow var(--transition);
}

.header.scrolled {
    box-shadow: 0 2px 20px rgba(0,0,0,0.08);
}

.header-inner {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 20px;
    font-weight: 700;
    color: var(--text);
}

.nav {
    display: flex;
    gap: 32px;
}

.nav a {
    font-size: 15px;
    font-weight: 500;
    color: var(--text-secondary);
    position: relative;
    padding: 4px 0;
}

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

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

.nav a:hover::after {
    width: 100%;
}

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

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

/* ========== Buttons ========== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 28px;
    border-radius: 8px;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: all var(--transition);
    white-space: nowrap;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(77,140,245,0.35);
}

.btn-outline {
    background: transparent;
    color: var(--primary);
    border: 2px solid var(--primary);
}

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

.btn-lg {
    padding: 16px 36px;
    font-size: 17px;
    border-radius: 10px;
}

.btn-block {
    width: 100%;
}

/* ========== Hero ========== */
.hero {
    position: relative;
    padding: 160px 0 100px;
    overflow: hidden;
    background: linear-gradient(135deg, #f0f5ff 0%, #e8f4f8 50%, #f5f0ff 100%);
}

.hero-bg {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse 600px 400px at 20% 50%, rgba(77,140,245,0.12) 0%, transparent 70%),
        radial-gradient(ellipse 500px 300px at 80% 30%, rgba(212,56,44,0.08) 0%, transparent 70%);
}

.hero-content {
    position: relative;
    text-align: center;
}

.hero h1 {
    font-size: 52px;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 16px;
    background: linear-gradient(135deg, var(--text), var(--primary-dark));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 22px;
    color: var(--text-secondary);
    margin-bottom: 12px;
    font-weight: 500;
}

.hero-desc {
    font-size: 16px;
    color: var(--text-light);
    margin-bottom: 36px;
    line-height: 1.8;
}

.hero-actions {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 20px;
}

.hero-meta {
    font-size: 13px;
    color: var(--text-light);
}

/* ========== Stats ========== */
.stats {
    padding: 48px 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 32px;
    text-align: center;
}

.stat-number {
    font-size: 36px;
    font-weight: 800;
    color: var(--primary);
    margin-bottom: 4px;
}

.stat-label {
    font-size: 14px;
    color: var(--text-light);
}

/* ========== Sections ========== */
.section {
    padding: 100px 0;
}

.section:nth-child(even) {
    background: var(--bg-gray);
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-header h2 {
    font-size: 36px;
    font-weight: 800;
    margin-bottom: 12px;
    color: var(--text);
}

.section-header p {
    font-size: 17px;
    color: var(--text-light);
    max-width: 640px;
    margin: 0 auto;
}

.badge {
    display: inline-block;
    background: linear-gradient(135deg, var(--primary), #7B61FF);
    color: #fff;
    padding: 4px 14px;
    border-radius: 20px;
    font-size: 13px;
    font-weight: 700;
    letter-spacing: 1px;
    margin-bottom: 12px;
}

/* ========== Features ========== */
.features-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 28px;
}

.feature-card {
    background: var(--bg);
    border-radius: var(--radius-lg);
    padding: 36px;
    border: 1px solid var(--border);
    transition: all var(--transition);
}

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

.feature-icon {
    width: 60px;
    height: 60px;
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
}

.feature-card h3 {
    font-size: 22px;
    font-weight: 700;
    margin-bottom: 12px;
}

.feature-card p {
    font-size: 15px;
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 16px;
}

.feature-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    list-style: none;
}

.feature-tags li {
    background: var(--primary-light);
    color: var(--primary-dark);
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 13px;
    font-weight: 500;
}

/* ========== AI Section ========== */
.ai-section {
    background: linear-gradient(135deg, #0f0c29, #302b63, #24243e) !important;
    color: #fff;
}

.ai-section .section-header h2 {
    color: #fff;
}

.ai-section .section-header p {
    color: rgba(255,255,255,0.7);
}

.ai-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
}

.ai-card {
    background: rgba(255,255,255,0.06);
    border: 1px solid rgba(255,255,255,0.1);
    border-radius: var(--radius-lg);
    padding: 36px;
    transition: all var(--transition);
    backdrop-filter: blur(10px);
}

.ai-card:hover {
    background: rgba(255,255,255,0.1);
    transform: translateY(-4px);
    box-shadow: 0 8px 32px rgba(0,0,0,0.3);
}

.ai-card-icon {
    font-size: 36px;
    margin-bottom: 16px;
}

.ai-card h3 {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 10px;
}

.ai-card p {
    font-size: 15px;
    color: rgba(255,255,255,0.7);
    line-height: 1.8;
}

/* ========== Smart Docs ========== */
.smart-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px;
}

.smart-card {
    background: var(--bg);
    border-radius: var(--radius-lg);
    padding: 40px 32px;
    text-align: center;
    border: 1px solid var(--border);
    transition: all var(--transition);
}

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

.smart-icon {
    font-size: 42px;
    margin-bottom: 16px;
}

.smart-card h3 {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 12px;
}

.smart-card p {
    font-size: 15px;
    color: var(--text-secondary);
    line-height: 1.8;
}

/* ========== Platform Section ========== */
.platform-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.platform-card {
    background: var(--bg);
    border-radius: var(--radius-lg);
    padding: 36px 24px;
    text-align: center;
    border: 1px solid var(--border);
    transition: all var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
}

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

.platform-icon {
    margin-bottom: 16px;
}

.platform-card h3 {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 10px;
}

.platform-card p {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 12px;
}

.platform-version {
    font-size: 13px;
    color: var(--text-light);
    margin-bottom: 20px;
}

.platform-card .btn {
    margin-top: auto;
    width: 100%;
}

/* ========== Advantages ========== */
.advantages-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px;
}

.advantage-item {
    text-align: center;
    padding: 32px 24px;
}

.advantage-icon {
    font-size: 42px;
    margin-bottom: 16px;
}

.advantage-item h3 {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 10px;
}

.advantage-item p {
    font-size: 15px;
    color: var(--text-secondary);
    line-height: 1.8;
}

/* ========== Enterprise Section ========== */
.enterprise-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.enterprise-text h2 {
    font-size: 36px;
    font-weight: 800;
    margin-bottom: 16px;
}

.highlight {
    color: var(--primary);
}

.enterprise-text > p {
    font-size: 16px;
    color: var(--text-secondary);
    margin-bottom: 24px;
    line-height: 1.8;
}

.enterprise-features {
    list-style: none;
}

.enterprise-features li {
    font-size: 15px;
    padding: 8px 0;
    color: var(--text-secondary);
}

.enterprise-visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.enterprise-card-stack {
    position: relative;
    width: 300px;
    height: 280px;
}

.e-card {
    position: absolute;
    width: 240px;
    padding: 24px 32px;
    border-radius: var(--radius);
    font-size: 18px;
    font-weight: 700;
    color: #fff;
    box-shadow: var(--shadow-lg);
    transition: all var(--transition);
}

.e-card-1 {
    background: var(--primary);
    top: 0;
    left: 0;
    transform: rotate(-6deg);
}

.e-card-2 {
    background: var(--green);
    top: 50px;
    left: 40px;
    transform: rotate(-2deg);
}

.e-card-3 {
    background: var(--red);
    top: 100px;
    left: 20px;
    transform: rotate(2deg);
}

.e-card-4 {
    background: linear-gradient(135deg, var(--primary), #7B61FF);
    top: 160px;
    left: 50px;
    transform: rotate(-1deg);
    font-size: 22px;
}

.enterprise-card-stack:hover .e-card {
    transform: rotate(0deg) translateX(10px);
}

/* ========== Download Section ========== */
.download-section {
    background: linear-gradient(135deg, #f0f5ff, #fff, #f5f0ff) !important;
}

.download-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.download-card {
    background: var(--bg);
    border-radius: var(--radius-lg);
    padding: 36px 24px;
    text-align: center;
    border: 1px solid var(--border);
    transition: all var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
}

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

.download-icon {
    margin-bottom: 20px;
}

.download-card h3 {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 8px;
}

.download-card > p {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 12px;
}

.download-info {
    display: block;
    font-size: 13px;
    color: var(--text-light);
    margin-bottom: 4px;
}

.download-info:last-of-type {
    margin-bottom: 20px;
}

.download-card .btn {
    margin-top: auto;
}

/* ========== FAQ ========== */
.faq-list {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    border: 1px solid var(--border);
    border-radius: var(--radius);
    margin-bottom: 12px;
    overflow: hidden;
    background: var(--bg);
    transition: all var(--transition);
}

.faq-item:hover {
    border-color: var(--primary);
}

.faq-question {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px;
    background: none;
    border: none;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    color: var(--text);
    text-align: left;
    gap: 16px;
}

.faq-arrow {
    flex-shrink: 0;
    transition: transform var(--transition);
    color: var(--text-light);
}

.faq-item.active .faq-arrow {
    transform: rotate(180deg);
    color: var(--primary);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease, padding 0.4s ease;
}

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

.faq-answer p {
    padding: 0 24px 20px;
    font-size: 15px;
    color: var(--text-secondary);
    line-height: 1.8;
}

/* ========== SEO Section ========== */
.seo-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.seo-card {
    background: var(--bg);
    border-radius: var(--radius);
    padding: 28px;
    border: 1px solid var(--border);
}

.seo-card h3 {
    font-size: 18px;
    font-weight: 700;
    margin-bottom: 10px;
    color: var(--text);
}

.seo-card p {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.9;
}

/* ========== Footer ========== */
.footer {
    background: var(--bg-dark);
    color: rgba(255,255,255,0.8);
    padding: 60px 0 30px;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 40px;
    margin-bottom: 48px;
}

.footer-col h4 {
    font-size: 16px;
    font-weight: 700;
    color: #fff;
    margin-bottom: 16px;
}

.footer-col a {
    display: block;
    font-size: 14px;
    color: rgba(255,255,255,0.6);
    padding: 4px 0;
    transition: color var(--transition);
}

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

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

.footer-seo p {
    font-size: 13px;
    color: rgba(255,255,255,0.4);
    line-height: 1.8;
    margin-bottom: 16px;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 24px;
    margin-bottom: 16px;
}

.footer-links a {
    font-size: 13px;
    color: rgba(255,255,255,0.5);
}

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

.copyright {
    font-size: 13px;
    color: rgba(255,255,255,0.35);
}

/* ========== Back to Top ========== */
.back-to-top {
    position: fixed;
    bottom: 32px;
    right: 32px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--primary);
    color: #fff;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all var(--transition);
    box-shadow: 0 4px 16px rgba(77,140,245,0.3);
    z-index: 999;
}

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

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

/* ========== Animations ========== */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ========== Responsive ========== */
@media (max-width: 1024px) {
    .features-grid,
    .ai-grid {
        grid-template-columns: repeat(2, 1fr);
    }

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

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

    .enterprise-content {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .enterprise-visual {
        order: -1;
    }

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

@media (max-width: 768px) {
    .nav {
        display: none;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: var(--bg);
        flex-direction: column;
        padding: 20px 24px;
        gap: 0;
        border-bottom: 1px solid var(--border);
        box-shadow: var(--shadow);
    }

    .nav.open {
        display: flex;
    }

    .nav a {
        padding: 12px 0;
        border-bottom: 1px solid var(--border);
    }

    .menu-toggle {
        display: flex;
    }

    .hero {
        padding: 120px 0 60px;
    }

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

    .hero-subtitle {
        font-size: 18px;
    }

    .hero-desc br {
        display: none;
    }

    .section {
        padding: 60px 0;
    }

    .section-header {
        margin-bottom: 40px;
    }

    .section-header h2 {
        font-size: 28px;
    }

    .features-grid,
    .ai-grid,
    .platform-grid,
    .download-grid {
        grid-template-columns: 1fr;
    }

    .advantages-grid,
    .smart-grid,
    .seo-grid {
        grid-template-columns: 1fr;
    }

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

    .stat-number {
        font-size: 28px;
    }

    .footer-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 24px;
    }

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

    .btn-lg {
        width: 100%;
        max-width: 320px;
    }
}

@media (max-width: 480px) {
    .stats-grid {
        grid-template-columns: 1fr 1fr;
    }

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

    .footer-links {
        flex-wrap: wrap;
        gap: 12px;
    }

    .enterprise-card-stack {
        width: 240px;
        height: 240px;
    }

    .e-card {
        width: 200px;
        padding: 18px 24px;
        font-size: 15px;
    }
}