:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary: #64748b;
    --dark: #1e293b;
    --light: #f8fafc;
    --white: #ffffff;
    --border: #e2e8f0;
    --shadow: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -2px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -4px rgba(0,0,0,0.1);
    --radius: 12px;
    --radius-sm: 8px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", sans-serif;
    font-size: 16px;
    line-height: 1.7;
    color: #334155;
    background: var(--light);
}

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

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

a {
    color: var(--primary);
    text-decoration: none;
    transition: color 0.2s;
}

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

h1, h2, h3, h4 {
    color: var(--dark);
    line-height: 1.3;
}

h1 {
    font-size: 2.5rem;
    font-weight: 700;
}

h2 {
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

p {
    margin-bottom: 1rem;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 24px;
    font-size: 1rem;
    font-weight: 500;
    border-radius: var(--radius-sm);
    border: none;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    color: var(--white);
    text-decoration: none;
}

.btn-secondary {
    background: var(--white);
    color: var(--dark);
    border: 1px solid var(--border);
}

.btn-secondary:hover {
    background: var(--light);
    text-decoration: none;
}

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

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

.btn-lg {
    padding: 16px 32px;
    font-size: 1.1rem;
}

.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: var(--white);
    box-shadow: var(--shadow);
    z-index: 1000;
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.logo-wrap {
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo-img {
    width: 40px;
    height: 40px;
    border-radius: 8px;
}

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--dark);
}

.nav-main {
    display: flex;
}

.nav-list {
    display: flex;
    list-style: none;
    gap: 8px;
}

.nav-list a {
    display: block;
    padding: 8px 14px;
    color: var(--secondary);
    font-size: 0.95rem;
    border-radius: var(--radius-sm);
    transition: all 0.2s;
}

.nav-list a:hover {
    color: var(--primary);
    background: rgba(37, 99, 235, 0.08);
    text-decoration: none;
}

.btn-nav-chat {
    background: var(--primary);
    color: var(--white);
    padding: 10px 20px;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    cursor: pointer;
    transition: background 0.2s;
}

.btn-nav-chat:hover {
    background: var(--primary-dark);
}

.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 8px;
    background: none;
    border: none;
    cursor: pointer;
}

.mobile-menu-btn span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--dark);
    transition: all 0.2s;
}

.hero {
    position: relative;
    min-height: 600px;
    padding-top: 70px;
    display: flex;
    align-items: center;
    overflow: hidden;
}

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

.hero-bg::after {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, rgba(30, 41, 59, 0.85) 0%, rgba(30, 41, 59, 0.6) 100%);
}

.hero-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.hero-content {
    position: relative;
    z-index: 1;
    padding: 60px 20px;
    max-width: 800px;
}

.breadcrumb {
    font-size: 0.875rem;
    color: rgba(255,255,255,0.7);
    margin-bottom: 20px;
}

.breadcrumb a {
    color: rgba(255,255,255,0.8);
}

.breadcrumb a:hover {
    color: var(--white);
}

.hero h1 {
    color: var(--white);
    margin-bottom: 20px;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: rgba(255,255,255,0.9);
    margin-bottom: 16px;
}

.hero-date {
    font-size: 0.9rem;
    color: rgba(255,255,255,0.7);
    margin-bottom: 30px;
}

.hero-actions {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

.section {
    padding: 80px 0;
}

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

.section-desc {
    color: var(--secondary);
    font-size: 1.1rem;
    margin-bottom: 40px;
    max-width: 700px;
}

.intro-grid {
    display: grid;
    grid-template-columns: 1fr 400px;
    gap: 50px;
    align-items: start;
}

.intro-text p {
    font-size: 1.05rem;
}

.intro-image img {
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
    margin-bottom: 40px;
}

.feature-card {
    background: var(--white);
    padding: 30px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    transition: transform 0.2s, box-shadow 0.2s;
}

.section:nth-child(even) .feature-card {
    background: var(--light);
}

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

.feature-card img {
    width: 100%;
    max-height: 200px;
    object-fit: cover;
    border-radius: var(--radius-sm);
    margin-bottom: 20px;
}

.features-cta {
    text-align: center;
    padding-top: 20px;
}

.features-cta p {
    margin-bottom: 16px;
    color: var(--secondary);
}

.download-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 50px;
    align-items: center;
}

.download-info h3 {
    margin-top: 24px;
}

.download-actions {
    display: flex;
    gap: 16px;
    margin-top: 30px;
    flex-wrap: wrap;
}

.download-preview {
    text-align: center;
}

.phone-frame {
    display: inline-block;
    background: var(--dark);
    padding: 15px 10px 25px;
    border-radius: 30px;
    box-shadow: var(--shadow-lg);
}

.phone-frame img {
    border-radius: 20px;
    max-width: 270px;
}

.app-carousel {
    display: flex;
    gap: 10px;
    justify-content: center;
    margin-top: 20px;
}

.app-carousel img {
    width: 80px;
    border-radius: 8px;
    box-shadow: var(--shadow);
}

.guide-list {
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.guide-item {
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: 30px;
    align-items: start;
    background: var(--white);
    padding: 30px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.section:nth-child(even) .guide-item {
    background: var(--light);
}

.guide-item:nth-child(even) {
    grid-template-columns: 1fr;
}

.guide-item img {
    border-radius: var(--radius-sm);
    width: 100%;
}

.guide-cta {
    text-align: center;
    margin-top: 40px;
    padding: 30px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    border-radius: var(--radius);
    color: var(--white);
}

.guide-cta p {
    margin-bottom: 16px;
    font-size: 1.1rem;
}

.guide-cta .btn-primary {
    background: var(--white);
    color: var(--primary);
}

.faq-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
    max-width: 900px;
    margin: 0 auto;
}

.faq-item {
    background: var(--white);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.section:nth-child(even) .faq-item {
    background: var(--light);
}

.faq-item summary {
    padding: 20px 24px;
    font-weight: 600;
    cursor: pointer;
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.faq-item summary::after {
    content: "+";
    font-size: 1.5rem;
    color: var(--primary);
    transition: transform 0.2s;
}

.faq-item[open] summary::after {
    transform: rotate(45deg);
}

.faq-answer {
    padding: 0 24px 20px;
    border-top: 1px solid var(--border);
    margin-top: -1px;
    padding-top: 20px;
}

.faq-more {
    text-align: center;
    margin-top: 40px;
}

.faq-more p {
    color: var(--secondary);
    margin-bottom: 16px;
}

.security-header {
    margin-bottom: 40px;
    border-radius: var(--radius);
    overflow: hidden;
}

.security-header img {
    width: 100%;
    max-height: 300px;
    object-fit: cover;
}

.security-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
    margin-bottom: 40px;
}

.security-card {
    background: var(--white);
    padding: 24px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.section:nth-child(even) .security-card {
    background: var(--light);
}

.security-warning {
    background: linear-gradient(135deg, #fef3c7 0%, #fde68a 100%);
    padding: 24px 30px;
    border-radius: var(--radius);
    border-left: 4px solid #f59e0b;
}

.security-warning h3 {
    color: #92400e;
    margin-bottom: 12px;
}

.security-warning p {
    color: #78350f;
    margin-bottom: 0;
}

.news-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.news-card {
    background: var(--white);
    padding: 24px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.section:nth-child(even) .news-card {
    background: var(--light);
}

.news-card h3 {
    font-size: 1.1rem;
}

.news-date {
    display: block;
    font-size: 0.875rem;
    color: var(--secondary);
    margin-top: 12px;
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    align-items: center;
}

.about-image img {
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 400px;
    gap: 40px;
    align-items: center;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    padding: 50px;
    border-radius: var(--radius);
    color: var(--white);
}

.contact-info p {
    font-size: 1.1rem;
    opacity: 0.95;
}

.contact-actions {
    margin-top: 24px;
}

.contact-actions .btn-primary {
    background: var(--white);
    color: var(--primary);
}

.contact-image img {
    border-radius: var(--radius);
}

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

.footer-main {
    display: grid;
    grid-template-columns: 250px 1fr;
    gap: 60px;
    margin-bottom: 40px;
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: 12px;
}

.footer-brand span {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--white);
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
}

.footer-col h4 {
    color: var(--white);
    font-size: 1rem;
    margin-bottom: 16px;
}

.footer-col ul {
    list-style: none;
}

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

.footer-col a {
    color: rgba(255,255,255,0.7);
    font-size: 0.95rem;
}

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

.footer-bottom {
    border-top: 1px solid rgba(255,255,255,0.1);
    padding-top: 24px;
    text-align: center;
    font-size: 0.9rem;
}

.btn-back-top {
    position: fixed;
    bottom: 100px;
    right: 20px;
    width: 48px;
    height: 48px;
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: 50%;
    font-size: 1.2rem;
    cursor: pointer;
    box-shadow: var(--shadow);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s;
    z-index: 999;
}

.btn-back-top.visible {
    opacity: 1;
    visibility: visible;
}

.btn-back-top:hover {
    background: var(--primary);
    color: var(--white);
    border-color: var(--primary);
}

.btn-float-chat {
    position: fixed;
    bottom: 30px;
    right: 20px;
    background: var(--primary);
    color: var(--white);
    border: none;
    padding: 14px 24px;
    border-radius: 30px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    box-shadow: var(--shadow-lg);
    transition: all 0.2s;
    z-index: 999;
}

.btn-float-chat:hover {
    background: var(--primary-dark);
    transform: scale(1.05);
}

@media (max-width: 1024px) {
    .nav-main {
        display: none;
    }
    
    .btn-nav-chat {
        display: none;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .intro-grid {
        grid-template-columns: 1fr;
    }
    
    .intro-image {
        order: -1;
        text-align: center;
    }
    
    .intro-image img {
        max-width: 300px;
        margin: 0 auto;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .download-grid {
        grid-template-columns: 1fr;
    }
    
    .download-preview {
        order: -1;
    }
    
    .guide-item {
        grid-template-columns: 1fr;
    }
    
    .guide-item img {
        max-width: 300px;
    }
    
    .security-grid {
        grid-template-columns: 1fr;
    }
    
    .news-grid {
        grid-template-columns: 1fr;
    }
    
    .about-content {
        grid-template-columns: 1fr;
    }
    
    .contact-content {
        grid-template-columns: 1fr;
        padding: 30px;
    }
    
    .footer-main {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    
    .footer-links {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    h1 {
        font-size: 1.75rem;
    }
    
    h2 {
        font-size: 1.5rem;
    }
    
    .hero {
        min-height: 500px;
    }
    
    .hero-content {
        padding: 40px 20px;
    }
    
    .hero-subtitle {
        font-size: 1.1rem;
    }
    
    .hero-actions {
        flex-direction: column;
    }
    
    .hero-actions .btn {
        width: 100%;
    }
    
    .section {
        padding: 50px 0;
    }
    
    .download-actions {
        flex-direction: column;
    }
    
    .download-actions .btn {
        width: 100%;
    }
    
    .phone-frame img {
        max-width: 200px;
    }
    
    .app-carousel img {
        width: 60px;
    }
    
    .footer-links {
        grid-template-columns: 1fr;
        gap: 24px;
    }
    
    .btn-float-chat {
        bottom: 20px;
        right: 15px;
        padding: 12px 20px;
        font-size: 0.95rem;
    }
    
    .btn-back-top {
        bottom: 80px;
        right: 15px;
        width: 44px;
        height: 44px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .header-inner {
        height: 60px;
    }
    
    .logo-img {
        width: 32px;
        height: 32px;
    }
    
    .logo-text {
        font-size: 1.25rem;
    }
    
    h1 {
        font-size: 1.5rem;
    }
    
    h2 {
        font-size: 1.35rem;
    }
    
    .feature-card {
        padding: 20px;
    }
    
    .faq-item summary {
        padding: 16px 20px;
        font-size: 0.95rem;
    }
    
    .faq-answer {
        padding: 0 20px 16px;
    }
}

.nav-mobile {
    position: fixed;
    top: 70px;
    left: 0;
    right: 0;
    background: var(--white);
    box-shadow: var(--shadow);
    padding: 20px;
    display: none;
    z-index: 999;
}

.nav-mobile.active {
    display: block;
}

.nav-mobile ul {
    list-style: none;
}

.nav-mobile li {
    margin-bottom: 8px;
}

.nav-mobile a {
    display: block;
    padding: 12px 16px;
    color: var(--dark);
    border-radius: var(--radius-sm);
}

.nav-mobile a:hover {
    background: var(--light);
    text-decoration: none;
}

.nav-mobile .btn-mobile-chat {
    width: 100%;
    margin-top: 16px;
}