* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
    color: #1f2937;
    background: #f6f8fc;
    line-height: 1.7;
    overflow-x: hidden;
}

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

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

.container {
    width: min(1120px, calc(100% - 32px));
    margin: 0 auto;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(255,255,255,.94);
    border-bottom: 1px solid #e7ecf4;
    backdrop-filter: blur(14px);
}

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

.logo {
    width: 40px;
    height: 40px;
    border-radius: 12px;
    object-fit: cover;
}

.brand,
.footer-brand {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    font-weight: 800;
    color: #111827;
    letter-spacing: .3px;
}

.brand span,
.footer-brand span {
    font-size: 19px;
}

.site-nav {
    display: none;
    flex-direction: column;
    gap: 8px;
    position: absolute;
    left: 16px;
    right: 16px;
    top: 70px;
    padding: 16px;
    border: 1px solid #e5eaf2;
    border-radius: 22px;
    background: #fff;
    box-shadow: 0 18px 45px rgba(41, 128, 254, .12);
}

.site-nav a {
    padding: 10px 12px;
    border-radius: 12px;
    color: #4b5563;
    font-size: 15px;
}

.site-nav a:hover,
.site-nav a.active {
    color: #2980FE;
    background: #eef5ff;
}

.nav-toggle {
    display: none;
}

.nav-toggle-label {
    display: inline-flex;
    width: 44px;
    height: 44px;
    border-radius: 14px;
    border: 1px solid #dde5f1;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    background: #fff;
}

.nav-toggle-label span {
    width: 20px;
    height: 2px;
    background: #1f2937;
    border-radius: 2px;
}

.nav-toggle:checked ~ .site-nav {
    display: flex;
}

.download-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 48px;
    padding: 0 28px;
    border-radius: 999px;
    background: #2980FE;
    color: #fff;
    font-weight: 800;
    box-shadow: 0 12px 28px rgba(41,128,254,.28);
    transition: transform .2s ease, background .2s ease, box-shadow .2s ease;
}

.download-btn:hover {
    background: #1768E8;
    transform: translateY(-2px);
    box-shadow: 0 16px 34px rgba(23,104,232,.32);
}

.text-link {
    color: #2980FE;
    font-weight: 700;
}

.text-link:hover {
    color: #1768E8;
}

.gradient-bg,
.vpn-network-hero,
.cta-section {
    background: linear-gradient(90deg, #3558F2 0%, #7B4EF1 50%, #B84DDA 100%);
}

.vpn-network-hero {
    position: relative;
    overflow: hidden;
    padding: 74px 0 48px;
    color: #fff;
}

.vpn-network-hero::before,
.vpn-network-hero::after {
    content: "";
    position: absolute;
    pointer-events: none;
    border-radius: 999px;
}

.vpn-network-hero::before {
    width: 760px;
    height: 760px;
    right: -330px;
    top: -320px;
    background: radial-gradient(circle, rgba(255,255,255,.26), rgba(255,255,255,0) 62%);
}

.vpn-network-hero::after {
    width: 520px;
    height: 520px;
    left: -240px;
    bottom: -260px;
    background: radial-gradient(circle, rgba(255,255,255,.18), rgba(255,255,255,0) 66%);
}

.hero-grid,
.split-section,
.feature-layout,
.privacy-layout,
.device-layout,
.protocol-layout,
.download-layout,
.about-layout {
    display: grid;
    grid-template-columns: 1fr;
    gap: 30px;
    align-items: center;
}

.hero-content,
.hero-visual,
.vpn-network-hero .container {
    position: relative;
    z-index: 2;
}

.eyebrow,
.category-badge {
    display: inline-flex;
    align-items: center;
    width: fit-content;
    gap: 8px;
    padding: 7px 13px;
    border-radius: 999px;
    background: #eef5ff;
    color: #2980FE;
    font-size: 13px;
    font-weight: 800;
}

.hero-content .eyebrow {
    background: rgba(255,255,255,.18);
    color: #fff;
    border: 1px solid rgba(255,255,255,.26);
}

.hero-content h1 {
    margin: 18px 0 16px;
    font-size: clamp(34px, 8vw, 64px);
    line-height: 1.08;
    letter-spacing: -1.4px;
}

.hero-content p {
    margin: 0 0 22px;
    max-width: 650px;
    color: rgba(255,255,255,.88);
    font-size: 17px;
}

.hero-tags,
.inline-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 18px;
}

.hero-tags span,
.inline-tags span {
    display: inline-flex;
    padding: 8px 12px;
    border-radius: 999px;
    font-size: 13px;
    font-weight: 700;
}

.hero-tags span {
    background: rgba(255,255,255,.15);
    border: 1px solid rgba(255,255,255,.22);
    color: #fff;
}

.inline-tags span {
    color: #2868d9;
    background: #eef5ff;
}

.hero-visual {
    min-height: 360px;
    border: 1px solid rgba(255,255,255,.22);
    border-radius: 32px;
    padding: 24px;
    background:
        linear-gradient(135deg, rgba(255,255,255,.20), rgba(255,255,255,.08)),
        radial-gradient(circle at 24% 36%, rgba(255,255,255,.30), transparent 6%),
        radial-gradient(circle at 64% 22%, rgba(255,255,255,.22), transparent 5%),
        radial-gradient(circle at 78% 72%, rgba(255,255,255,.22), transparent 7%);
    box-shadow: inset 0 0 0 1px rgba(255,255,255,.12), 0 30px 80px rgba(9,21,72,.22);
}

.hero-device {
    width: min(420px, 88%);
    margin: 0 auto;
    border-radius: 28px;
    filter: drop-shadow(0 24px 44px rgba(0,0,0,.22));
}

.float-card {
    position: absolute;
    z-index: 3;
    padding: 10px 14px;
    border-radius: 18px;
    background: rgba(255,255,255,.92);
    color: #21304a;
    font-weight: 800;
    font-size: 13px;
    box-shadow: 0 12px 26px rgba(0,0,0,.12);
}

.float-card small {
    display: block;
    color: #6b7280;
    font-weight: 600;
    line-height: 1.3;
}

.float-1 { top: 26px; left: 22px; }
.float-2 { top: 78px; right: 18px; }
.float-3 { bottom: 80px; left: 16px; }
.float-4 { bottom: 24px; right: 26px; }

.section {
    padding: 72px 0;
}

.section-soft {
    background: #eef4fb;
}

.section-head {
    max-width: 780px;
    margin: 0 auto 32px;
    text-align: center;
}

.section-head h2,
.content-block h2,
.page-hero h1 {
    margin: 10px 0 12px;
    line-height: 1.18;
    color: #111827;
}

.section-head h2,
.content-block h2 {
    font-size: clamp(28px, 5vw, 42px);
}

.section-head p,
.content-block p,
.page-hero p,
.card p,
.info-panel p,
.faq-item p,
.step-card p,
.risk-card p {
    color: #5f6b7a;
}

.node-overview {
    margin-top: -36px;
    position: relative;
    z-index: 5;
}

.node-overview-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 16px;
}

.node-card,
.card,
.info-panel,
.faq-item,
.step-card,
.risk-card,
.download-card,
.about-card {
    background: #fff;
    border: 1px solid #e5ebf3;
    border-radius: 24px;
    box-shadow: 0 14px 34px rgba(31, 41, 55, .06);
}

.node-card {
    padding: 22px;
}

.node-card .tag,
.card .tag,
.info-panel .tag {
    display: inline-flex;
    margin-bottom: 10px;
    padding: 5px 10px;
    border-radius: 999px;
    color: #2980FE;
    background: #eef5ff;
    font-size: 12px;
    font-weight: 800;
}

.node-card h3,
.card h3,
.info-panel h3,
.step-card h3,
.risk-card h3 {
    margin: 0 0 8px;
    color: #111827;
}

.node-card p,
.card p,
.info-panel p,
.step-card p,
.risk-card p {
    margin: 0 0 12px;
}

.vpn-connection-section .image-frame,
.high-speed-section .image-frame,
.multi-device-section .image-frame,
.privacy-protection-section .image-frame,
.encryption-protocol-section .image-frame {
    padding: 18px;
    border-radius: 32px;
    background: #fff;
    border: 1px solid #e5ebf3;
    box-shadow: 0 20px 60px rgba(41, 128, 254, .11);
}

.image-frame img {
    border-radius: 24px;
    width: 100%;
    object-fit: cover;
}

.feature-list {
    list-style: none;
    padding: 0;
    margin: 20px 0;
    display: grid;
    gap: 12px;
}

.feature-list li {
    padding: 14px 16px;
    border-left: 4px solid #2980FE;
    border-radius: 16px;
    background: #f7faff;
    color: #374151;
}

.global-nodes-section {
    position: relative;
    overflow: hidden;
    background:
        radial-gradient(circle at 18% 20%, rgba(41,128,254,.14), transparent 22%),
        radial-gradient(circle at 82% 74%, rgba(123,78,241,.12), transparent 26%),
        #fff;
}

.map-panel {
    position: relative;
    min-height: 340px;
    border-radius: 32px;
    padding: 24px;
    background:
        linear-gradient(135deg, rgba(41,128,254,.12), rgba(184,77,218,.08)),
        repeating-linear-gradient(90deg, transparent 0, transparent 58px, rgba(41,128,254,.09) 59px, transparent 60px),
        repeating-linear-gradient(0deg, transparent 0, transparent 58px, rgba(41,128,254,.08) 59px, transparent 60px);
    border: 1px solid #e1eaf7;
}

.map-panel img {
    margin: 22px auto;
    width: min(430px, 92%);
    border-radius: 26px;
    filter: drop-shadow(0 20px 40px rgba(41,128,254,.16));
}

.node-dot {
    position: absolute;
    width: 13px;
    height: 13px;
    border: 3px solid #fff;
    border-radius: 50%;
    background: #2980FE;
    box-shadow: 0 0 0 10px rgba(41,128,254,.14);
}

.node-a { top: 22%; left: 24%; }
.node-b { top: 44%; right: 22%; }
.node-c { bottom: 24%; left: 48%; }

.speed-cards,
.privacy-cards,
.policy-grid,
.protocol-grid,
.risk-grid,
.faq-grid,
.card-grid,
.related-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 18px;
}

.speed-line {
    padding: 18px;
    border-radius: 20px;
    background: #fff;
    border: 1px solid #e5ebf3;
}

.speed-line strong {
    display: flex;
    justify-content: space-between;
    color: #111827;
}

.speed-bar {
    height: 8px;
    margin-top: 12px;
    border-radius: 999px;
    background: #dbeafe;
    overflow: hidden;
}

.speed-bar span {
    display: block;
    height: 100%;
    border-radius: 999px;
    background: #2980FE;
}

.privacy-panel,
.protocol-panel {
    padding: 24px;
    border-radius: 32px;
    background: #fff;
    border: 1px solid #e5ebf3;
    box-shadow: 0 20px 60px rgba(31,41,55,.06);
}

.security-layer {
    padding: 18px;
    border-radius: 22px;
    background: linear-gradient(135deg, #eef5ff, #fff);
    border: 1px solid #dce8fa;
    margin-bottom: 14px;
}

.policy-grid .card,
.privacy-cards .card,
.protocol-grid .card,
.related-grid .card,
.card-grid .card {
    padding: 22px;
}

.device-card-stack {
    display: grid;
    gap: 14px;
}

.device-mini {
    padding: 18px;
    border-radius: 22px;
    background: #fff;
    border: 1px solid #e5ebf3;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
}

.device-mini span {
    font-weight: 800;
    color: #111827;
}

.protocol-grid .card {
    background: linear-gradient(180deg, #fff, #f7faff);
}

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

.step-card {
    padding: 22px;
    position: relative;
}

.step-number {
    width: 38px;
    height: 38px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 14px;
    background: #2980FE;
    color: #fff;
    font-weight: 900;
    margin-bottom: 14px;
}

.risk-card {
    padding: 22px;
    border-left: 5px solid #2980FE;
}

.faq-item {
    padding: 22px;
}

.faq-item h3 {
    margin: 0 0 8px;
    color: #111827;
    font-size: 18px;
}

.cta-section {
    color: #fff;
    padding: 58px 0;
    text-align: center;
}

.cta-section h2 {
    margin: 0 0 12px;
    font-size: clamp(28px, 5vw, 44px);
}

.cta-section p {
    max-width: 720px;
    margin: 0 auto 24px;
    color: rgba(255,255,255,.86);
}

.page-hero {
    padding: 54px 0 34px;
    background:
        radial-gradient(circle at 12% 0%, rgba(41,128,254,.15), transparent 26%),
        radial-gradient(circle at 88% 24%, rgba(184,77,218,.12), transparent 22%),
        #fff;
    border-bottom: 1px solid #e7ecf4;
}

.page-hero h1 {
    font-size: clamp(34px, 6vw, 56px);
}

.page-layout {
    display: grid;
    grid-template-columns: 1fr;
    gap: 22px;
    align-items: start;
}

.article-content {
    background: #fff;
    border: 1px solid #e5ebf3;
    border-radius: 28px;
    padding: 24px;
    box-shadow: 0 16px 38px rgba(31,41,55,.05);
}

.article-content h2 {
    margin-top: 0;
    color: #111827;
}

.article-content p {
    color: #4b5563;
}

.check-list,
.number-list {
    margin: 18px 0;
    padding: 0;
    list-style: none;
    display: grid;
    gap: 12px;
}

.check-list li,
.number-list li {
    padding: 14px 16px;
    border-radius: 16px;
    background: #f7faff;
    border: 1px solid #e1eaf7;
}

.aside-panel {
    padding: 22px;
    border-radius: 24px;
    background: #fff;
    border: 1px solid #e5ebf3;
    position: sticky;
    top: 94px;
}

.aside-panel a {
    display: block;
    color: #2980FE;
    font-weight: 700;
    margin-top: 10px;
}

.download-card {
    padding: 28px;
    text-align: center;
    margin-top: 22px;
}

.download-layout .download-card {
    margin-top: 0;
}

.site-footer {
    padding: 52px 0 22px;
    background: #111827;
    color: #d1d5db;
}

.footer-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 26px;
}

.footer-brand {
    color: #fff;
}

.footer-brand img {
    width: 38px;
    height: 38px;
    border-radius: 12px;
    object-fit: cover;
}

.site-footer h3 {
    margin: 0 0 12px;
    color: #fff;
    font-size: 16px;
}

.site-footer a {
    display: block;
    color: #cbd5e1;
    margin: 8px 0;
}

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

.footer-bottom {
    margin-top: 28px;
    padding-top: 22px;
    border-top: 1px solid rgba(255,255,255,.1);
    color: #9ca3af;
    font-size: 14px;
}

@media (min-width: 680px) {
    .node-overview-grid,
    .speed-cards,
    .privacy-cards,
    .policy-grid,
    .protocol-grid,
    .risk-grid,
    .faq-grid,
    .card-grid,
    .related-grid {
        grid-template-columns: repeat(2, 1fr);
    }

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

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

    .article-content {
        padding: 32px;
    }
}

@media (min-width: 980px) {
    .nav-toggle-label {
        display: none;
    }

    .site-nav {
        display: flex;
        position: static;
        flex-direction: row;
        align-items: center;
        gap: 2px;
        padding: 0;
        border: 0;
        border-radius: 0;
        background: transparent;
        box-shadow: none;
    }

    .site-nav a {
        font-size: 14px;
        padding: 9px 10px;
    }

    .hero-grid,
    .split-section,
    .feature-layout,
    .privacy-layout,
    .device-layout,
    .protocol-layout,
    .download-layout,
    .about-layout {
        grid-template-columns: 1.02fr .98fr;
        gap: 54px;
    }

    .hero-visual {
        min-height: 460px;
    }

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

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

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

    .page-layout {
        grid-template-columns: minmax(0, 1fr) 300px;
        gap: 28px;
    }

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

    .section {
        padding: 86px 0;
    }
}

@media (min-width: 1180px) {
    .site-nav a {
        padding: 10px 13px;
    }
}

@media (max-width: 420px) {
    .container {
        width: min(100% - 24px, 1120px);
    }

    .download-btn {
        width: 100%;
        min-height: 52px;
    }

    .float-card {
        position: static;
        display: inline-block;
        margin: 8px 6px 0 0;
    }

    .hero-visual {
        min-height: auto;
    }

    .hero-device {
        width: 100%;
    }
}