* {
    box-sizing: border-box;
}

:root {
    --gradient: linear-gradient(90deg, #3558F2 0%, #7B4EF1 50%, #B84DDA 100%);
    --blue: #2980FE;
    --blue-dark: #1768E8;
    --text: #1f2937;
    --muted: #667085;
    --light: #f6f8fc;
    --line: #e5eaf3;
    --panel: #ffffff;
    --soft-blue: #eef5ff;
    --shadow: 0 18px 45px rgba(39, 76, 142, 0.12);
    --radius-lg: 32px;
    --radius-md: 22px;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", "PingFang SC", Arial, sans-serif;
    color: var(--text);
    background: #ffffff;
    line-height: 1.7;
    overflow-x: hidden;
}

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

a {
    color: inherit;
    text-decoration: none;
}

p {
    margin: 0 0 16px;
    color: var(--muted);
}

h1, h2, h3 {
    margin: 0;
    color: #182034;
    line-height: 1.25;
}

.container {
    width: min(100% - 32px, 1180px);
    margin: 0 auto;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(255, 255, 255, 0.92);
    backdrop-filter: blur(18px);
    border-bottom: 1px solid rgba(229, 234, 243, 0.9);
}

.header-inner {
    min-height: 70px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 18px;
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    font-weight: 800;
    color: #182034;
    flex-shrink: 0;
}

.logo-img {
    width: 42px;
    height: 42px;
    object-fit: contain;
    border-radius: 12px;
}

.brand-text {
    font-size: 18px;
    letter-spacing: 0.02em;
}

.main-nav {
    display: none;
    position: absolute;
    left: 16px;
    right: 16px;
    top: 70px;
    background: #fff;
    border: 1px solid var(--line);
    border-radius: 18px;
    padding: 12px;
    box-shadow: var(--shadow);
}

.main-nav a {
    display: block;
    padding: 11px 12px;
    color: #4d5b73;
    border-radius: 12px;
    font-size: 15px;
}

.main-nav a.active,
.main-nav a:hover {
    color: var(--blue);
    background: var(--soft-blue);
}

.nav-toggle {
    display: none;
}

.nav-toggle-label {
    width: 42px;
    height: 42px;
    border: 1px solid var(--line);
    border-radius: 14px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 5px;
    cursor: pointer;
}

.nav-toggle-label span {
    width: 18px;
    height: 2px;
    background: #1f2937;
    border-radius: 10px;
}

.nav-toggle:checked ~ .main-nav {
    display: block;
}

.download-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 48px;
    padding: 13px 24px;
    border-radius: 999px;
    background: var(--blue);
    color: #ffffff;
    font-weight: 800;
    box-shadow: 0 12px 28px rgba(41, 128, 254, 0.28);
    transition: transform 0.2s ease, background 0.2s ease, box-shadow 0.2s ease;
}

.download-btn:hover {
    background: var(--blue-dark);
    transform: translateY(-2px);
    box-shadow: 0 16px 32px rgba(23, 104, 232, 0.28);
}

.section {
    padding: 68px 0;
}

.section-soft {
    background: var(--light);
}

.section-title {
    max-width: 760px;
    margin-bottom: 30px;
}

.section-title.center {
    margin-left: auto;
    margin-right: auto;
    text-align: center;
}

.section-title h2 {
    font-size: clamp(26px, 4vw, 42px);
    margin-bottom: 12px;
}

.section-title p {
    font-size: 17px;
}

.badge,
.category-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--blue);
    background: var(--soft-blue);
    border: 1px solid rgba(41, 128, 254, 0.16);
    border-radius: 999px;
    padding: 6px 12px;
    font-size: 13px;
    font-weight: 800;
    margin-bottom: 14px;
}

.vpn-network-hero {
    position: relative;
    overflow: hidden;
    color: #fff;
    background: var(--gradient);
    padding: 64px 0 48px;
}

.vpn-network-hero::before {
    content: "";
    position: absolute;
    inset: 0;
    background:
        radial-gradient(circle at 14% 20%, rgba(255,255,255,0.24), transparent 28%),
        radial-gradient(circle at 78% 28%, rgba(255,255,255,0.18), transparent 25%),
        linear-gradient(135deg, rgba(255,255,255,0.12) 1px, transparent 1px);
    background-size: auto, auto, 48px 48px;
    opacity: 0.75;
}

.hero-grid {
    position: relative;
    display: grid;
    grid-template-columns: 1fr;
    gap: 34px;
    align-items: center;
}

.hero-copy h1 {
    font-size: clamp(34px, 8vw, 64px);
    color: #fff;
    letter-spacing: -0.03em;
    margin-bottom: 18px;
}

.hero-copy p {
    color: rgba(255,255,255,0.86);
    font-size: 17px;
    max-width: 650px;
}

.hero-tags,
.status-tags,
.inline-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin: 20px 0 26px;
}

.hero-tags span,
.status-tags span,
.inline-tags span {
    border: 1px solid rgba(255,255,255,0.25);
    background: rgba(255,255,255,0.13);
    color: #fff;
    border-radius: 999px;
    padding: 7px 12px;
    font-size: 13px;
    font-weight: 700;
}

.hero-visual {
    position: relative;
    min-height: 330px;
}

.hero-device-card {
    position: relative;
    width: min(100%, 430px);
    margin: 0 auto;
    padding: 18px;
    border-radius: var(--radius-lg);
    background: rgba(255,255,255,0.16);
    border: 1px solid rgba(255,255,255,0.24);
    box-shadow: 0 30px 80px rgba(27, 35, 90, 0.24);
}

.hero-device-card img {
    border-radius: 26px;
    margin: 0 auto;
}

.floating-status {
    position: absolute;
    background: #fff;
    color: #182034;
    border-radius: 18px;
    padding: 10px 14px;
    font-size: 13px;
    font-weight: 800;
    box-shadow: 0 14px 36px rgba(23, 35, 74, 0.18);
}

.floating-status:nth-of-type(1) { top: 10px; left: 0; }
.floating-status:nth-of-type(2) { top: 32%; right: -4px; }
.floating-status:nth-of-type(3) { bottom: 62px; left: 8px; }
.floating-status:nth-of-type(4) { bottom: 10px; right: 18px; }

.node-overview {
    margin-top: -34px;
    position: relative;
    z-index: 3;
}

.node-grid,
.card-grid,
.risk-grid,
.faq-summary-grid,
.policy-grid,
.device-grid,
.protocol-grid,
.related-grid,
.check-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 18px;
}

.node-card,
.info-card,
.risk-card,
.faq-item,
.policy-card,
.device-card,
.protocol-card,
.related-card,
.check-card {
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: var(--radius-md);
    padding: 22px;
    box-shadow: 0 12px 30px rgba(20, 34, 67, 0.06);
}

.node-card .mini-label,
.info-card .mini-label,
.risk-card .mini-label {
    display: inline-flex;
    color: var(--blue);
    background: var(--soft-blue);
    border-radius: 999px;
    padding: 4px 10px;
    font-size: 12px;
    font-weight: 800;
    margin-bottom: 12px;
}

.node-card h3,
.info-card h3,
.risk-card h3,
.faq-item h3,
.policy-card h3,
.device-card h3,
.protocol-card h3,
.related-card h3,
.check-card h3 {
    font-size: 20px;
    margin-bottom: 9px;
}

.text-link {
    color: var(--blue);
    font-weight: 800;
}

.split-section,
.vpn-connection-section,
.global-nodes-section,
.high-speed-section,
.privacy-protection-section,
.multi-device-section,
.encryption-protocol-section {
    display: grid;
    grid-template-columns: 1fr;
    gap: 28px;
    align-items: center;
}

.visual-panel,
.content-panel,
.privacy-panel,
.speed-panel,
.node-map-panel,
.protocol-panel {
    border-radius: var(--radius-lg);
    background: #fff;
    border: 1px solid var(--line);
    padding: 24px;
    box-shadow: var(--shadow);
}

.content-panel ul,
.article-body ul,
.article-body ol,
.step-list,
.clean-list {
    padding-left: 20px;
    color: var(--muted);
}

.content-panel li,
.article-body li,
.step-list li,
.clean-list li {
    margin-bottom: 8px;
}

.global-bg {
    position: relative;
    overflow: hidden;
    background: linear-gradient(135deg, #f7faff, #ffffff);
}

.global-bg::before {
    content: "";
    position: absolute;
    inset: 28px;
    border-radius: var(--radius-lg);
    background-image:
        radial-gradient(circle at 22% 32%, rgba(41,128,254,0.18) 0 6px, transparent 7px),
        radial-gradient(circle at 70% 22%, rgba(123,78,241,0.16) 0 6px, transparent 7px),
        radial-gradient(circle at 58% 68%, rgba(184,77,218,0.14) 0 6px, transparent 7px),
        linear-gradient(90deg, transparent, rgba(41,128,254,0.12), transparent);
    opacity: 0.88;
}

.node-map-panel {
    position: relative;
    min-height: 330px;
    display: grid;
    place-items: center;
}

.node-map-panel img,
.visual-panel img,
.speed-panel img,
.privacy-panel img,
.protocol-panel img {
    margin: 0 auto;
    border-radius: 26px;
}

.speed-lines {
    display: grid;
    gap: 12px;
    margin-top: 18px;
}

.speed-line {
    background: #fff;
    border: 1px solid var(--line);
    border-radius: 18px;
    padding: 14px;
}

.line-meter {
    height: 8px;
    background: #e9eef7;
    border-radius: 999px;
    overflow: hidden;
    margin-top: 10px;
}

.line-meter span {
    display: block;
    height: 100%;
    border-radius: 999px;
    background: var(--blue);
}

.safety-panel {
    background: #fff;
    border: 1px solid var(--line);
    border-left: 5px solid var(--blue);
    border-radius: var(--radius-md);
    padding: 22px;
    box-shadow: 0 12px 30px rgba(20, 34, 67, 0.07);
}

.process-steps {
    display: grid;
    grid-template-columns: 1fr;
    gap: 16px;
    counter-reset: step;
}

.process-step {
    position: relative;
    background: #fff;
    border: 1px solid var(--line);
    border-radius: var(--radius-md);
    padding: 22px;
    box-shadow: 0 12px 30px rgba(20, 34, 67, 0.06);
}

.process-step .step-num {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: var(--blue);
    color: #fff;
    font-weight: 800;
    margin-bottom: 12px;
}

.risk-card {
    border-top: 4px solid var(--blue);
}

.faq-item details {
    cursor: pointer;
}

.faq-item summary {
    font-weight: 800;
    color: #182034;
    list-style: none;
}

.faq-item summary::-webkit-details-marker {
    display: none;
}

.faq-item p {
    margin-top: 12px;
}

.cta-section {
    padding: 64px 0;
    background: var(--gradient);
    color: #fff;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.cta-section::before {
    content: "";
    position: absolute;
    inset: 0;
    background: radial-gradient(circle at 20% 30%, rgba(255,255,255,0.22), transparent 24%), radial-gradient(circle at 80% 70%, rgba(255,255,255,0.16), transparent 28%);
}

.cta-section .container {
    position: relative;
}

.cta-section h2 {
    color: #fff;
    font-size: clamp(26px, 4vw, 42px);
    margin-bottom: 12px;
}

.cta-section p {
    color: rgba(255,255,255,0.86);
    max-width: 680px;
    margin: 0 auto 24px;
}

.page-hero {
    padding: 62px 0 36px;
    background: linear-gradient(180deg, #f5f8ff 0%, #ffffff 100%);
}

.page-hero .container {
    max-width: 980px;
}

.page-hero h1 {
    font-size: clamp(32px, 6vw, 54px);
    margin-bottom: 16px;
}

.page-hero p {
    font-size: 17px;
    max-width: 780px;
}

.article-layout {
    display: grid;
    grid-template-columns: 1fr;
    gap: 24px;
    padding: 30px 0 68px;
}

.article-body {
    background: #fff;
    border: 1px solid var(--line);
    border-radius: var(--radius-lg);
    padding: 24px;
    box-shadow: 0 12px 30px rgba(20, 34, 67, 0.06);
}

.article-body h2 {
    font-size: 26px;
    margin: 28px 0 12px;
}

.article-body h2:first-child {
    margin-top: 0;
}

.aside-panel {
    display: grid;
    gap: 16px;
    align-content: start;
}

.tip-box {
    background: var(--soft-blue);
    border: 1px solid rgba(41,128,254,0.14);
    border-radius: var(--radius-md);
    padding: 20px;
}

.simple-cta {
    margin-top: 24px;
    padding-top: 24px;
    border-top: 1px solid var(--line);
}

.download-page-panel {
    max-width: 960px;
    margin: 30px auto 68px;
    display: grid;
    grid-template-columns: 1fr;
    gap: 24px;
}

.download-card {
    background: #fff;
    border: 1px solid var(--line);
    border-radius: var(--radius-lg);
    padding: 28px;
    box-shadow: var(--shadow);
    text-align: center;
}

.site-footer {
    background: #101828;
    color: #d6dce8;
    padding: 54px 0 26px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 28px;
}

.footer-brand {
    color: #fff;
    font-weight: 900;
    font-size: 22px;
    margin-bottom: 12px;
}

.site-footer p {
    color: #aeb8c8;
}

.site-footer h3 {
    color: #fff;
    font-size: 16px;
    margin-bottom: 12px;
}

.site-footer a {
    display: block;
    color: #aeb8c8;
    margin-bottom: 8px;
}

.site-footer a:hover {
    color: #fff;
}

.footer-bottom {
    border-top: 1px solid rgba(255,255,255,0.12);
    margin-top: 34px;
    padding-top: 18px;
    display: flex;
    flex-direction: column;
    gap: 8px;
    color: #98a2b3;
    font-size: 14px;
}

@media (min-width: 640px) {
    .node-grid,
    .card-grid,
    .risk-grid,
    .faq-summary-grid,
    .policy-grid,
    .device-grid,
    .protocol-grid,
    .related-grid,
    .check-grid,
    .process-steps {
        grid-template-columns: repeat(2, 1fr);
    }

    .download-page-panel {
        grid-template-columns: 1.1fr 0.9fr;
        align-items: start;
    }
}

@media (min-width: 900px) {
    .nav-toggle-label {
        display: none;
    }

    .main-nav {
        display: flex;
        align-items: center;
        gap: 4px;
        position: static;
        padding: 0;
        border: 0;
        box-shadow: none;
        background: transparent;
    }

    .main-nav a {
        display: inline-flex;
        padding: 9px 12px;
    }

    .vpn-network-hero {
        padding: 94px 0 86px;
    }

    .hero-grid,
    .split-section,
    .vpn-connection-section,
    .global-nodes-section,
    .high-speed-section,
    .privacy-protection-section,
    .multi-device-section,
    .encryption-protocol-section {
        grid-template-columns: 1fr 1fr;
        gap: 54px;
    }

    .node-grid {
        grid-template-columns: repeat(4, 1fr);
    }

    .policy-grid,
    .device-grid,
    .protocol-grid,
    .risk-grid {
        grid-template-columns: repeat(3, 1fr);
    }

    .process-steps {
        grid-template-columns: repeat(3, 1fr);
    }

    .article-layout {
        grid-template-columns: minmax(0, 1fr) 320px;
        align-items: start;
    }

    .article-body {
        padding: 34px;
    }

    .footer-grid {
        grid-template-columns: 1.5fr 1fr 1fr 1fr;
    }

    .footer-bottom {
        flex-direction: row;
        justify-content: space-between;
    }
}

@media (min-width: 1120px) {
    .faq-summary-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

.content-panel .inline-tags span,
.article-body .inline-tags span {
    color: var(--blue);
    background: var(--soft-blue);
    border: 1px solid rgba(41,128,254,0.16);
}