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

:root {
    --primary-color: #0052FF;
    --secondary-color: #1E1E1E;
    --accent-color: #00D4AA;
    --text-dark: #1A1A1A;
    --text-gray: #666666;
    --text-light: #999999;
    --bg-light: #F8F9FA;
    --bg-white: #FFFFFF;
    --border-color: #E5E5E5;
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.12);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.16);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-white);
    overflow-x: hidden;
}

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

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

button {
    cursor: pointer;
    border: none;
    background: none;
    font-family: inherit;
    transition: var(--transition);
}

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

.section {
    padding: 80px 0;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.section-subtitle {
    font-size: 1.125rem;
    text-align: center;
    color: var(--text-gray);
    margin-bottom: 3rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

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

.header.scrolled {
    box-shadow: var(--shadow-md);
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo-icon {
    width: 32px;
    height: 32px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 700;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

.nav-link {
    color: var(--text-dark);
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
}

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

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

.nav-cta {
    background: var(--primary-color);
    color: white;
    padding: 0.625rem 1.5rem;
    border-radius: 50px;
    font-weight: 600;
}

.nav-cta:hover {
    background: #0041CC;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.mobile-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    padding: 0.5rem;
}

.mobile-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text-dark);
    transition: var(--transition);
}

.hero {
    padding-top: 120px;
    padding-bottom: 80px;
    background: linear-gradient(135deg, #F0F4FF 0%, #E8F5F3 100%);
    position: relative;
    overflow: hidden;
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-text h1 {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 1.5rem;
    color: var(--text-dark);
}

.hero-text .highlight {
    color: var(--primary-color);
    position: relative;
    display: inline-block;
}

.hero-text p {
    font-size: 1.25rem;
    color: var(--text-gray);
    margin-bottom: 2rem;
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.btn {
    padding: 1rem 2rem;
    border-radius: 50px;
    font-weight: 600;
    font-size: 1rem;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: var(--transition);
}

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

.btn-primary:hover {
    background: #0041CC;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

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

.hero-image {
    position: relative;
}

.hero-image img {
    width: 100%;
    border-radius: 20px;
    box-shadow: var(--shadow-lg);
}

.hero-features {
    display: flex;
    gap: 2rem;
    margin-top: 3rem;
}

.hero-feature {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.hero-feature-icon {
    width: 48px;
    height: 48px;
    background: white;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
    font-size: 1.5rem;
    box-shadow: var(--shadow-sm);
}

.hero-feature-text strong {
    display: block;
    color: var(--text-dark);
    font-weight: 600;
}

.hero-feature-text span {
    color: var(--text-gray);
    font-size: 0.875rem;
}

.products {
    background: var(--bg-white);
}

.products-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.product-card {
    background: white;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

.product-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.product-image {
    position: relative;
    padding: 2rem;
    background: var(--bg-light);
    text-align: center;
}

.product-badge {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: var(--accent-color);
    color: white;
    padding: 0.375rem 0.875rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
}

.product-image img {
    width: 100%;
    max-width: 250px;
    margin: 0 auto;
}

.product-info {
    padding: 1.5rem;
}

.product-title {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}

.product-subtitle {
    color: var(--text-gray);
    margin-bottom: 1rem;
    font-size: 0.875rem;
}

.product-features {
    list-style: none;
    margin-bottom: 1.5rem;
}

.product-features li {
    padding: 0.5rem 0;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-gray);
    font-size: 0.875rem;
}

.product-features li::before {
    content: '鉁�';
    color: var(--accent-color);
    font-weight: 700;
}

.product-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.product-price {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.product-btn {
    background: var(--primary-color);
    color: white;
    padding: 0.625rem 1.5rem;
    border-radius: 50px;
    font-weight: 600;
    font-size: 0.875rem;
}

.product-btn:hover {
    background: #0041CC;
}

.comparison {
    background: var(--bg-light);
}

.comparison-table {
    background: white;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.comparison-header {
    display: grid;
    grid-template-columns: 200px repeat(4, 1fr);
    background: var(--secondary-color);
    color: white;
    font-weight: 600;
    text-align: center;
}

.comparison-header > div {
    padding: 1.5rem 1rem;
    border-right: 1px solid rgba(255,255,255,0.1);
}

.comparison-header > div:last-child {
    border-right: none;
}

.comparison-row {
    display: grid;
    grid-template-columns: 200px repeat(4, 1fr);
    border-bottom: 1px solid var(--border-color);
}

.comparison-row:last-child {
    border-bottom: none;
}

.comparison-feature {
    padding: 1.25rem 1rem;
    font-weight: 600;
    color: var(--text-dark);
    border-right: 1px solid var(--border-color);
    display: flex;
    align-items: center;
}

.comparison-value {
    padding: 1.25rem 1rem;
    text-align: center;
    color: var(--text-gray);
    border-right: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: center;
}

.comparison-value:last-child {
    border-right: none;
}

.check-icon {
    color: var(--accent-color);
    font-size: 1.25rem;
}

.tutorials {
    background: var(--bg-white);
}

.tutorials-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.tutorial-card {
    background: white;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

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

.tutorial-image {
    position: relative;
    overflow: hidden;
    height: 220px;
}

.tutorial-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition);
}

.tutorial-card:hover .tutorial-image img {
    transform: scale(1.05);
}

.tutorial-category {
    position: absolute;
    top: 1rem;
    left: 1rem;
    background: var(--primary-color);
    color: white;
    padding: 0.375rem 0.875rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
}

.tutorial-content {
    padding: 1.5rem;
}

.tutorial-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    color: var(--text-dark);
}

.tutorial-description {
    color: var(--text-gray);
    margin-bottom: 1rem;
    line-height: 1.6;
}

.tutorial-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
    font-size: 0.875rem;
    color: var(--text-light);
}

.security {
    background: linear-gradient(135deg, #1E1E1E 0%, #2D2D2D 100%);
    color: white;
}

.security .section-title,
.security .section-subtitle {
    color: white;
}

.security-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.security-card {
    background: rgba(255,255,255,0.05);
    border: 1px solid rgba(255,255,255,0.1);
    border-radius: 16px;
    padding: 2rem;
    text-align: center;
    transition: var(--transition);
}

.security-card:hover {
    background: rgba(255,255,255,0.08);
    transform: translateY(-4px);
}

.security-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 1.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
}

.security-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
}

.security-card p {
    color: rgba(255,255,255,0.7);
    line-height: 1.8;
}

.faq {
    background: var(--bg-light);
}

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

.faq-item {
    background: white;
    border-radius: 12px;
    margin-bottom: 1rem;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.faq-question {
    width: 100%;
    text-align: left;
    padding: 1.5rem;
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-dark);
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
}

.faq-question:hover {
    background: var(--bg-light);
}

.faq-icon {
    font-size: 1.5rem;
    color: var(--primary-color);
    transition: var(--transition);
}

.faq-item.active .faq-icon {
    transform: rotate(45deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
}

.faq-answer-content {
    padding: 0 1.5rem 1.5rem;
    color: var(--text-gray);
    line-height: 1.8;
}

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

.cta {
    background: linear-gradient(135deg, var(--primary-color) 0%, #0041CC 100%);
    color: white;
    text-align: center;
}

.cta .section-title,
.cta .section-subtitle {
    color: white;
}

.cta-content {
    max-width: 600px;
    margin: 0 auto;
}

.cta-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

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

.btn-white:hover {
    background: var(--bg-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-outline-white {
    border: 2px solid white;
    color: white;
    background: transparent;
}

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

.footer {
    background: var(--secondary-color);
    color: rgba(255,255,255,0.8);
    padding: 3rem 0 1.5rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 3rem;
    margin-bottom: 2rem;
}

.footer-section h3 {
    color: white;
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    font-weight: 700;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 0.75rem;
}

.footer-links a {
    color: rgba(255,255,255,0.7);
    transition: var(--transition);
}

.footer-links a:hover {
    color: white;
    padding-left: 5px;
}

.footer-social {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
}

.social-icon {
    width: 40px;
    height: 40px;
    background: rgba(255,255,255,0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    transition: var(--transition);
}

.social-icon:hover {
    background: var(--primary-color);
    transform: translateY(-2px);
}

.footer-bottom {
    border-top: 1px solid rgba(255,255,255,0.1);
    padding-top: 1.5rem;
    text-align: center;
    color: rgba(255,255,255,0.6);
    font-size: 0.875rem;
}

.friends-links {
    background: var(--bg-light);
    padding: 2rem 0;
}

.friends-title {
    text-align: center;
    color: var(--text-gray);
    font-size: 0.875rem;
    margin-bottom: 1rem;
    font-weight: 600;
}

.friends-list {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 2rem;
    list-style: none;
}

.friends-list a {
    color: var(--text-gray);
    font-size: 0.875rem;
    transition: var(--transition);
}

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

.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 999;
}

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

.back-to-top:hover {
    background: #0041CC;
    transform: translateY(-4px);
}

@media (max-width: 1024px) {
    .comparison-header,
    .comparison-row {
        grid-template-columns: 150px repeat(4, 1fr);
    }
    
    .hero-text h1 {
        font-size: 2.75rem;
    }
}

@media (max-width: 768px) {
    .section {
        padding: 60px 0;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .section-subtitle {
        font-size: 1rem;
    }
    
    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        background: white;
        flex-direction: column;
        padding: 2rem;
        box-shadow: var(--shadow-md);
        transition: var(--transition);
        align-items: flex-start;
        gap: 1rem;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .mobile-toggle {
        display: flex;
    }
    
    .mobile-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .mobile-toggle.active span:nth-child(2) {
        opacity: 0;
    }
    
    .mobile-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(6px, -6px);
    }
    
    .hero {
        padding-top: 100px;
        padding-bottom: 60px;
    }
    
    .hero-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .hero-text h1 {
        font-size: 2rem;
    }
    
    .hero-text p {
        font-size: 1rem;
    }
    
    .hero-features {
        flex-direction: column;
        gap: 1rem;
    }
    
    .products-grid {
        grid-template-columns: 1fr;
    }
    
    .comparison-table {
        overflow-x: auto;
    }
    
    .comparison-header,
    .comparison-row {
        grid-template-columns: 120px repeat(4, minmax(100px, 1fr));
        font-size: 0.875rem;
    }
    
    .comparison-header > div,
    .comparison-feature,
    .comparison-value {
        padding: 1rem 0.5rem;
    }
    
    .tutorials-grid {
        grid-template-columns: 1fr;
    }
    
    .security-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .cta-buttons,
    .hero-buttons {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
    
    .friends-list {
        gap: 1rem;
    }
    
    .back-to-top {
        bottom: 4rem;
        right: 1rem;
        width: 45px;
        height: 45px;
    }
}

@media (max-width: 480px) {
    .hero-text h1 {
        font-size: 1.75rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
    
    .comparison-header,
    .comparison-row {
        grid-template-columns: 100px repeat(4, minmax(80px, 1fr));
        font-size: 0.75rem;
    }
}