/* ============================================
   快连VPN - Global Styles
   ============================================ */

:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-light: #3b82f6;
    --primary-bg: #eff6ff;
    --accent: #06b6d4;
    --dark: #0f172a;
    --dark-soft: #1e293b;
    --text: #334155;
    --text-light: #64748b;
    --text-lighter: #94a3b8;
    --border: #e2e8f0;
    --border-light: #f1f5f9;
    --white: #ffffff;
    --bg: #f8fafc;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow: 0 4px 6px -1px rgba(0,0,0,0.07), 0 2px 4px -2px rgba(0,0,0,0.05);
    --shadow-md: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -4px rgba(0,0,0,0.05);
    --shadow-lg: 0 20px 25px -5px rgba(0,0,0,0.08), 0 8px 10px -6px rgba(0,0,0,0.04);
    --radius: 12px;
    --radius-lg: 20px;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
    color: var(--text);
    background: var(--white);
    line-height: 1.7;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

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

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

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

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

h1, h2, h3, h4 {
    color: var(--dark);
    line-height: 1.3;
    font-weight: 700;
}

/* ============================================
   Buttons
   ============================================ */

.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 32px;
    border-radius: 50px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    border: 2px solid transparent;
    text-decoration: none;
    white-space: nowrap;
}

.btn-primary {
    background: var(--primary);
    color: var(--white);
    border-color: var(--primary);
    box-shadow: 0 4px 14px rgba(37, 99, 235, 0.35);
}

.btn-primary:hover {
    background: var(--primary-dark);
    border-color: var(--primary-dark);
    color: var(--white);
    box-shadow: 0 6px 20px rgba(37, 99, 235, 0.45);
    transform: translateY(-2px);
}

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

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

.btn-lg {
    padding: 18px 42px;
    font-size: 18px;
}

/* ============================================
   Header
   ============================================ */

.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    transition: all var(--transition);
}

.header.scrolled {
    background: rgba(255, 255, 255, 0.95);
    box-shadow: var(--shadow);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 72px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 22px;
    font-weight: 700;
    color: var(--dark);
    text-decoration: none;
}

.logo:hover {
    color: var(--primary);
}

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

.nav {
    display: flex;
    align-items: center;
    gap: 32px;
}

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

.nav a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary);
    transition: width var(--transition);
}

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

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

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

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

.menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.menu-toggle.active span:nth-child(2) {
    opacity: 0;
}

.menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

/* ============================================
   Hero Section
   ============================================ */

.hero {
    position: relative;
    padding-top: 72px;
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 0;
}

.hero-bg img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    opacity: 0.08;
}

.hero-bg::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, #eff6ff 0%, #e0f2fe 30%, #f0f9ff 70%, #f8fafc 100%);
    z-index: 1;
}

.hero-content {
    position: relative;
    z-index: 2;
    display: flex;
    align-items: center;
    gap: 60px;
    padding: 80px 24px 60px;
    min-height: 560px;
}

.hero-text {
    flex: 1;
}

.hero-badge {
    display: inline-block;
    background: rgba(37, 99, 235, 0.1);
    color: var(--primary);
    padding: 6px 16px;
    border-radius: 50px;
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 20px;
}

.hero h1 {
    font-size: 52px;
    font-weight: 800;
    color: var(--dark);
    margin-bottom: 12px;
    letter-spacing: -1px;
}

.hero-subtitle {
    font-size: 20px;
    color: var(--primary);
    font-weight: 600;
    margin-bottom: 16px;
}

.hero-desc {
    font-size: 16px;
    color: var(--text-light);
    line-height: 1.8;
    margin-bottom: 32px;
    max-width: 540px;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
    margin-bottom: 28px;
}

.hero-platforms {
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--text-lighter);
    font-size: 14px;
}

.hero-platforms img {
    opacity: 0.6;
    transition: opacity var(--transition);
    border-radius: 4px;
}

.hero-platforms img:hover {
    opacity: 1;
}

.hero-image {
    flex: 0 0 auto;
    max-width: 460px;
}

.hero-image img {
    border-radius: var(--radius-lg);
    filter: drop-shadow(0 20px 40px rgba(37, 99, 235, 0.15));
}

/* Stats Bar */
.hero-stats {
    position: relative;
    z-index: 2;
    background: var(--white);
    border-top: 1px solid var(--border-light);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
    padding: 36px 24px;
}

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

.stat-item strong {
    display: block;
    font-size: 32px;
    font-weight: 800;
    color: var(--primary);
    margin-bottom: 4px;
}

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

/* ============================================
   Section Headers
   ============================================ */

.section-header {
    text-align: center;
    max-width: 680px;
    margin: 0 auto 56px;
}

.section-header h2 {
    font-size: 36px;
    margin-bottom: 16px;
    position: relative;
    display: inline-block;
}

.section-header h2::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 48px;
    height: 3px;
    background: var(--primary);
    border-radius: 3px;
}

.section-header p {
    color: var(--text-light);
    font-size: 16px;
    margin-top: 20px;
}

/* ============================================
   Features Section
   ============================================ */

.features {
    padding: 100px 0;
    background: var(--bg);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px;
}

.feature-card {
    background: var(--white);
    border-radius: var(--radius);
    padding: 36px 28px;
    transition: all var(--transition);
    border: 1px solid var(--border-light);
}

.feature-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: transparent;
}

.feature-icon {
    width: 72px;
    height: 72px;
    background: var(--primary-bg);
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
    overflow: hidden;
}

.feature-icon img {
    width: 48px;
    height: 48px;
    object-fit: contain;
}

.feature-card h3 {
    font-size: 20px;
    margin-bottom: 14px;
    color: var(--dark);
}

.feature-card p {
    font-size: 14px;
    color: var(--text-light);
    line-height: 1.8;
}

/* ============================================
   Protocols Section
   ============================================ */

.protocols {
    padding: 100px 0;
    background: var(--white);
}

.protocol-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px;
}

.protocol-card {
    background: var(--bg);
    border-radius: var(--radius);
    padding: 36px 28px;
    border: 1px solid var(--border-light);
    transition: all var(--transition);
    position: relative;
}

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

.protocol-icon {
    width: 64px;
    height: 64px;
    margin-bottom: 16px;
    border-radius: 12px;
    overflow: hidden;
    background: var(--white);
    display: flex;
    align-items: center;
    justify-content: center;
}

.protocol-icon img {
    width: 44px;
    height: 44px;
    object-fit: contain;
}

.protocol-card h3 {
    font-size: 20px;
    margin-bottom: 8px;
}

.protocol-tag {
    display: inline-block;
    background: rgba(37, 99, 235, 0.1);
    color: var(--primary);
    padding: 3px 12px;
    border-radius: 50px;
    font-size: 12px;
    font-weight: 600;
    margin-bottom: 14px;
}

.protocol-tag.tag-alt {
    background: rgba(16, 185, 129, 0.1);
    color: #059669;
}

.protocol-tag.tag-mobile {
    background: rgba(245, 158, 11, 0.1);
    color: #d97706;
}

.protocol-card p {
    font-size: 14px;
    color: var(--text-light);
    line-height: 1.8;
    margin-bottom: 16px;
}

.protocol-card ul {
    list-style: none;
    padding: 0;
}

.protocol-card ul li {
    font-size: 14px;
    color: var(--text);
    padding: 6px 0;
    padding-left: 20px;
    position: relative;
}

.protocol-card ul li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--primary);
    font-weight: 700;
    font-size: 13px;
}

/* ============================================
   Advantages Section
   ============================================ */

.advantages {
    padding: 100px 0;
    background: var(--bg);
}

.advantages-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 28px;
}

.advantage-card {
    background: var(--white);
    border-radius: var(--radius);
    padding: 36px 32px;
    border: 1px solid var(--border-light);
    transition: all var(--transition);
}

.advantage-card:hover {
    box-shadow: var(--shadow-md);
    border-color: transparent;
}

.advantage-icon {
    font-size: 28px;
    margin-bottom: 14px;
}

.advantage-card h3 {
    font-size: 19px;
    margin-bottom: 14px;
    color: var(--dark);
}

.advantage-card p {
    font-size: 14px;
    color: var(--text-light);
    line-height: 1.8;
}

/* ============================================
   Use Cases Section
   ============================================ */

.use-cases {
    padding: 100px 0;
    background: var(--white);
}

.cases-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 28px;
}

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

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

.case-card img {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

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

.case-content h3 {
    font-size: 18px;
    margin-bottom: 10px;
}

.case-content p {
    font-size: 14px;
    color: var(--text-light);
    line-height: 1.8;
}

/* ============================================
   FAQ Section
   ============================================ */

.faq {
    padding: 100px 0;
    background: var(--bg);
}

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

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

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

.faq-item.active {
    box-shadow: var(--shadow);
    border-color: rgba(37, 99, 235, 0.2);
}

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

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

.faq-question svg {
    flex-shrink: 0;
    transition: transform var(--transition);
    color: var(--text-lighter);
}

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

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease, padding 0.3s ease;
}

.faq-item.active .faq-answer {
    max-height: 600px;
    padding: 0 24px 24px;
}

.faq-answer p {
    font-size: 15px;
    color: var(--text-light);
    line-height: 1.8;
}

/* ============================================
   Updates Section
   ============================================ */

.updates {
    padding: 100px 0;
    background: var(--white);
}

.updates-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px;
}

.update-card {
    background: var(--bg);
    border-radius: var(--radius);
    padding: 32px 28px;
    border: 1px solid var(--border-light);
    transition: all var(--transition);
}

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

.update-date {
    font-size: 13px;
    color: var(--primary);
    font-weight: 600;
    margin-bottom: 12px;
    padding: 4px 12px;
    background: var(--primary-bg);
    display: inline-block;
    border-radius: 50px;
}

.update-card h3 {
    font-size: 17px;
    margin-bottom: 14px;
    line-height: 1.5;
    color: var(--dark);
}

.update-card p {
    font-size: 14px;
    color: var(--text-light);
    line-height: 1.8;
}

/* ============================================
   CTA Section
   ============================================ */

.cta-section {
    padding: 80px 0;
    background: linear-gradient(135deg, var(--dark) 0%, #1e3a5f 50%, var(--primary-dark) 100%);
    text-align: center;
}

.cta-content h2 {
    color: var(--white);
    font-size: 34px;
    margin-bottom: 16px;
}

.cta-content p {
    color: rgba(255, 255, 255, 0.7);
    font-size: 16px;
    margin-bottom: 36px;
}

.cta-content .btn-primary {
    background: var(--white);
    color: var(--primary-dark);
    border-color: var(--white);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
}

.cta-content .btn-primary:hover {
    background: var(--primary-bg);
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.3);
}

/* ============================================
   Footer
   ============================================ */

.footer {
    background: var(--dark);
    color: rgba(255, 255, 255, 0.6);
    padding-top: 64px;
}

.footer-inner {
    display: flex;
    gap: 60px;
    padding-bottom: 48px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

.footer-brand {
    flex: 1;
    max-width: 340px;
}

.footer-brand .logo {
    color: var(--white);
    margin-bottom: 16px;
}

.footer-brand .logo:hover {
    color: var(--primary-light);
}

.footer-brand p {
    font-size: 14px;
    line-height: 1.8;
}

.footer-links {
    display: flex;
    gap: 60px;
    flex: 1;
}

.footer-col h4 {
    color: var(--white);
    font-size: 15px;
    margin-bottom: 20px;
    font-weight: 600;
}

.footer-col a {
    display: block;
    color: rgba(255, 255, 255, 0.5);
    font-size: 14px;
    padding: 5px 0;
    transition: color var(--transition);
}

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

.footer-bottom {
    padding: 20px 0;
}

.footer-bottom p {
    font-size: 13px;
    color: rgba(255, 255, 255, 0.35);
    text-align: center;
}

/* ============================================
   Responsive Design
   ============================================ */

@media (max-width: 1024px) {
    .hero-content {
        padding: 60px 24px 40px;
    }

    .hero h1 {
        font-size: 42px;
    }

    .hero-image {
        max-width: 360px;
    }

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

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

    .nav {
        display: none;
        position: absolute;
        top: 72px;
        left: 0;
        right: 0;
        background: var(--white);
        flex-direction: column;
        padding: 20px 24px;
        gap: 0;
        box-shadow: var(--shadow-lg);
        border-top: 1px solid var(--border-light);
    }

    .nav.open {
        display: flex;
    }

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

    .nav a::after {
        display: none;
    }

    .hero-content {
        flex-direction: column;
        text-align: center;
        padding: 48px 24px 32px;
        min-height: auto;
    }

    .hero h1 {
        font-size: 34px;
    }

    .hero-subtitle {
        font-size: 17px;
    }

    .hero-desc {
        max-width: 100%;
    }

    .hero-buttons {
        justify-content: center;
    }

    .hero-platforms {
        justify-content: center;
    }

    .hero-image {
        max-width: 320px;
        margin: 0 auto;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 20px;
        padding: 28px 24px;
    }

    .stat-item strong {
        font-size: 26px;
    }

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

    .features,
    .protocols,
    .advantages,
    .use-cases,
    .faq,
    .updates {
        padding: 72px 0;
    }

    .features-grid,
    .protocol-grid,
    .advantages-grid,
    .cases-grid,
    .updates-grid {
        grid-template-columns: 1fr;
    }

    .footer-inner {
        flex-direction: column;
        gap: 36px;
    }

    .footer-brand {
        max-width: 100%;
    }

    .footer-links {
        flex-wrap: wrap;
        gap: 36px;
    }

    .footer-col {
        min-width: 140px;
    }

    .cta-content h2 {
        font-size: 26px;
    }

    .btn {
        padding: 12px 24px;
        font-size: 15px;
    }

    .btn-lg {
        padding: 14px 32px;
        font-size: 16px;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 28px;
    }

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

    .hero-buttons .btn {
        width: 100%;
        justify-content: center;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 16px;
    }

    .stat-item strong {
        font-size: 22px;
    }

    .section-header h2 {
        font-size: 24px;
    }

    .faq-question {
        font-size: 15px;
        padding: 16px 20px;
    }

    .faq-item.active .faq-answer {
        padding: 0 20px 20px;
    }
}

/* ============================================
   Animations
   ============================================ */

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(24px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-text {
    animation: fadeInUp 0.8s ease-out;
}

.hero-image {
    animation: fadeInUp 0.8s ease-out 0.2s both;
}

.feature-card,
.protocol-card,
.advantage-card,
.case-card,
.update-card,
.faq-item {
    animation: fadeInUp 0.6s ease-out both;
}

.feature-card:nth-child(1) { animation-delay: 0.05s; }
.feature-card:nth-child(2) { animation-delay: 0.1s; }
.feature-card:nth-child(3) { animation-delay: 0.15s; }
.feature-card:nth-child(4) { animation-delay: 0.2s; }
.feature-card:nth-child(5) { animation-delay: 0.25s; }
.feature-card:nth-child(6) { animation-delay: 0.3s; }