:root {
    --gradient: linear-gradient(90deg, #3558F2 0%, #7B4EF1 50%, #B84DDA 100%);
    --blue: #2980FE;
    --blue-dark: #1768E8;
    --text: #202A3A;
    --muted: #667085;
    --light: #F5F7FB;
    --line: #E5EAF2;
    --panel: #FFFFFF;
    --deep: #111827;
    --radius: 24px;
    --shadow: 0 18px 50px rgba(30, 54, 110, .10);
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif;
    color: var(--text);
    background: #fff;
    line-height: 1.7;
    overflow-x: hidden;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
p { margin: 0 0 14px; color: var(--muted); }
h1, h2, h3 { margin: 0; color: var(--deep); line-height: 1.25; }
h1 { font-size: clamp(34px, 9vw, 64px); letter-spacing: -1.6px; }
h2 { font-size: clamp(26px, 6vw, 42px); letter-spacing: -1px; }
h3 { font-size: 20px; }
ul, ol { padding-left: 20px; color: var(--muted); }
main { min-height: 70vh; }
.container, .section-inner, .footer-inner, .header-inner { width: min(1160px, calc(100% - 32px)); margin: 0 auto; }
.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(255,255,255,.92);
    backdrop-filter: blur(18px);
    border-bottom: 1px solid rgba(229,234,242,.9);
}
.header-inner {
    min-height: 70px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
}
.brand { display: flex; align-items: center; gap: 10px; font-size: 22px; font-weight: 800; color: #15213D; }
.logo { width: 42px; height: 42px; border-radius: 12px; object-fit: cover; box-shadow: 0 10px 26px rgba(41,128,254,.18); }
.nav-toggle { position: absolute; opacity: 0; pointer-events: none; }
.nav-toggle-label { display: grid; gap: 5px; cursor: pointer; padding: 10px; }
.nav-toggle-label span { width: 24px; height: 2px; background: #1D2939; border-radius: 99px; display: block; }
.site-nav {
    position: absolute;
    top: 70px;
    left: 16px;
    right: 16px;
    display: none;
    flex-direction: column;
    background: #fff;
    padding: 12px;
    border: 1px solid var(--line);
    border-radius: 18px;
    box-shadow: var(--shadow);
}
.nav-toggle:checked ~ .site-nav { display: flex; }
.site-nav a { padding: 10px 12px; border-radius: 12px; color: #344054; font-weight: 600; font-size: 15px; }
.site-nav a.active, .site-nav a:hover { background: #EEF5FF; color: var(--blue); }
.download-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 48px;
    padding: 12px 26px;
    background: var(--blue);
    color: #fff;
    border-radius: 999px;
    font-weight: 800;
    border: 0;
    box-shadow: 0 14px 30px rgba(41,128,254,.25);
    transition: transform .2s ease, background .2s ease, box-shadow .2s ease;
}
.download-btn:hover { background: var(--blue-dark); transform: translateY(-2px); box-shadow: 0 18px 36px rgba(41,128,254,.32); }
.pill, .badge, .mini-tag {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    width: fit-content;
    padding: 6px 12px;
    border-radius: 999px;
    background: #EEF5FF;
    color: var(--blue);
    font-weight: 800;
    font-size: 13px;
}
.vpn-network-hero {
    position: relative;
    overflow: hidden;
    background: var(--gradient);
    color: #fff;
    padding: 72px 0 50px;
}
.vpn-network-hero::before,
.vpn-network-hero::after {
    content: "";
    position: absolute;
    inset: auto;
    border-radius: 50%;
    background: rgba(255,255,255,.18);
    filter: blur(4px);
}
.vpn-network-hero::before { width: 360px; height: 360px; right: -120px; top: -110px; }
.vpn-network-hero::after { width: 260px; height: 260px; left: -110px; bottom: -100px; }
.hero-grid {
    position: relative;
    z-index: 1;
    display: grid;
    gap: 34px;
    align-items: center;
}
.hero-copy h1, .hero-copy p { color: #fff; }
.hero-copy p { font-size: 18px; opacity: .92; max-width: 680px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 14px; align-items: center; margin: 28px 0 20px; }
.hero-tags { display: flex; flex-wrap: wrap; gap: 10px; }
.hero-tags span { padding: 8px 12px; border-radius: 999px; color: #fff; background: rgba(255,255,255,.16); border: 1px solid rgba(255,255,255,.24); font-weight: 700; }
.hero-visual { position: relative; min-height: 300px; display: grid; place-items: center; }
.hero-device {
    width: min(430px, 100%);
    padding: 20px;
    border-radius: 32px;
    background: rgba(255,255,255,.17);
    border: 1px solid rgba(255,255,255,.25);
    box-shadow: 0 30px 70px rgba(18, 26, 67, .22);
}
.hero-device img { border-radius: 24px; width: 100%; height: auto; object-fit: cover; }
.float-card {
    position: absolute;
    display: none;
    padding: 10px 14px;
    color: #1D2939;
    background: rgba(255,255,255,.94);
    border-radius: 16px;
    font-weight: 800;
    box-shadow: 0 18px 40px rgba(17,24,39,.18);
}
.float-card.one { left: 0; top: 18%; }
.float-card.two { right: 0; top: 8%; }
.float-card.three { left: 8%; bottom: 6%; }
.float-card.four { right: 2%; bottom: 20%; }
.section { padding: 72px 0; }
.section.alt { background: var(--light); }
.section-head { margin-bottom: 28px; max-width: 780px; }
.section-head.center { margin-left: auto; margin-right: auto; text-align: center; }
.section-head p { font-size: 17px; margin-top: 12px; }
.node-overview { margin-top: -34px; position: relative; z-index: 4; }
.node-grid, .feature-grid, .risk-grid, .faq-grid, .log-grid, .device-grid, .protocol-grid, .link-grid { display: grid; gap: 16px; }
.node-card, .feature-card, .risk-card, .faq-item, .log-card, .device-card, .protocol-card, .step-card, .side-card, .info-card {
    background: var(--panel);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: 22px;
    box-shadow: 0 10px 35px rgba(30,54,110,.06);
}
.node-card h3, .feature-card h3, .risk-card h3 { margin: 10px 0 8px; }
.text-link { color: var(--blue); font-weight: 800; }
.text-link:hover { color: var(--blue-dark); }
.split-section { display: grid; gap: 28px; align-items: center; }
.visual-panel {
    background: #fff;
    border: 1px solid var(--line);
    border-radius: 32px;
    padding: 18px;
    box-shadow: var(--shadow);
}
.visual-panel img { width: 100%; border-radius: 24px; object-fit: cover; }
.check-list { display: grid; gap: 10px; margin: 18px 0 20px; padding: 0; list-style: none; }
.check-list li { position: relative; padding-left: 28px; color: #475467; }
.check-list li::before { content: ""; position: absolute; left: 0; top: 8px; width: 14px; height: 14px; border-radius: 50%; background: var(--blue); box-shadow: inset 0 0 0 4px #D8E9FF; }
.global-nodes-section {
    position: relative;
    overflow: hidden;
    background: #F7FAFF;
}
.global-nodes-section::before {
    content: "";
    position: absolute;
    inset: 50px 8% auto;
    height: 200px;
    background-image: radial-gradient(circle at 20% 30%, rgba(41,128,254,.30) 0 4px, transparent 5px), radial-gradient(circle at 70% 45%, rgba(123,78,241,.28) 0 4px, transparent 5px), radial-gradient(circle at 45% 75%, rgba(184,77,218,.24) 0 4px, transparent 5px);
    opacity: .85;
}
.map-panel { position: relative; z-index: 1; }
.map-card { background: rgba(255,255,255,.88); backdrop-filter: blur(12px); }
.speed-lines { display: grid; gap: 12px; margin-top: 18px; }
.speed-line { padding: 14px; background: #fff; border: 1px solid var(--line); border-radius: 18px; }
.speed-line span { display: flex; justify-content: space-between; color: #344054; font-weight: 800; margin-bottom: 8px; }
.track { height: 8px; background: #EAF0F8; border-radius: 999px; overflow: hidden; }
.track i { display: block; height: 100%; background: var(--blue); border-radius: 999px; }
.privacy-panel { background: #fff; border-radius: 32px; border: 1px solid var(--line); padding: 24px; box-shadow: var(--shadow); }
.boundary-list { display: grid; gap: 12px; margin-top: 18px; }
.boundary-list div { padding: 16px; border-radius: 18px; background: #F6F9FE; border: 1px solid var(--line); }
.process-steps { display: grid; gap: 16px; counter-reset: step; }
.step-card { position: relative; padding-top: 50px; }
.step-card::before {
    counter-increment: step;
    content: counter(step, decimal-leading-zero);
    position: absolute;
    top: 18px;
    left: 22px;
    color: var(--blue);
    font-weight: 900;
    letter-spacing: .5px;
}
.risk-card { border-left: 4px solid var(--blue); }
.faq-item summary { cursor: pointer; font-weight: 800; color: #1D2939; }
.faq-item p { margin-top: 12px; }
.cta-section { padding: 72px 0; background: var(--gradient); color: #fff; text-align: center; position: relative; overflow: hidden; }
.cta-section h2, .cta-section p { color: #fff; }
.cta-box { width: min(780px, calc(100% - 32px)); margin: 0 auto; position: relative; z-index: 1; }
.cta-section .download-btn { margin-top: 18px; }
.page-hero { padding: 64px 0 38px; background: linear-gradient(180deg, #F4F8FF 0%, #FFFFFF 100%); }
.page-hero .container { display: grid; gap: 14px; }
.page-hero p { max-width: 780px; font-size: 17px; }
.article-layout { width: min(1120px, calc(100% - 32px)); margin: 0 auto; padding: 52px 0 72px; display: grid; gap: 22px; }
.article-content { display: grid; gap: 22px; }
.article-content h2 { font-size: 28px; }
.article-block { background: #fff; border: 1px solid var(--line); border-radius: 28px; padding: 24px; box-shadow: 0 14px 40px rgba(30,54,110,.06); }
.article-block.highlight { background: #F7FAFF; }
.article-block .download-btn { margin-top: 10px; }
.side-panel { display: grid; gap: 16px; align-content: start; }
.side-card h3 { margin-bottom: 10px; }
.side-card a { display: block; padding: 9px 0; color: var(--blue); font-weight: 800; border-bottom: 1px solid #EEF2F7; }
.note-box { padding: 18px; border-radius: 20px; background: #F6F9FE; border: 1px solid var(--line); color: #475467; }
.download-page-card { text-align: center; background: #fff; border: 1px solid var(--line); border-radius: 32px; padding: 30px; box-shadow: var(--shadow); }
.numbered-list { display: grid; gap: 14px; padding: 0; list-style: none; counter-reset: item; }
.numbered-list li { position: relative; padding: 16px 16px 16px 54px; border: 1px solid var(--line); border-radius: 18px; background: #fff; color: #475467; }
.numbered-list li::before { counter-increment: item; content: counter(item); position: absolute; left: 16px; top: 16px; width: 26px; height: 26px; border-radius: 50%; background: var(--blue); color: #fff; display: grid; place-items: center; font-weight: 800; }
.site-footer { background: #101828; color: #D0D5DD; padding-top: 52px; }
.footer-inner { display: grid; gap: 28px; }
.footer-brand h2, .footer-links h3 { color: #fff; }
.footer-logo { width: 48px; height: 48px; border-radius: 14px; object-fit: cover; margin-bottom: 12px; }
.footer-links { display: grid; gap: 22px; }
.footer-links a { display: block; color: #D0D5DD; margin-top: 8px; }
.footer-links a:hover { color: #fff; }
.footer-bottom { margin-top: 34px; border-top: 1px solid rgba(255,255,255,.12); padding: 18px 16px; text-align: center; }
.footer-bottom p { color: #98A2B3; margin: 0; }
@media (min-width: 700px) {
    .node-grid { grid-template-columns: repeat(2, 1fr); }
    .feature-grid, .risk-grid, .log-grid, .device-grid, .protocol-grid, .faq-grid { grid-template-columns: repeat(2, 1fr); }
    .process-steps { grid-template-columns: repeat(2, 1fr); }
    .footer-links { grid-template-columns: repeat(3, 1fr); }
}
@media (min-width: 980px) {
    .nav-toggle-label { display: none; }
    .site-nav { position: static; display: flex; flex-direction: row; align-items: center; width: auto; padding: 0; border: 0; box-shadow: none; background: transparent; }
    .site-nav a { padding: 8px 11px; }
    .vpn-network-hero { padding: 96px 0 80px; }
    .hero-grid { grid-template-columns: 1.05fr .95fr; }
    .float-card { display: block; }
    .node-grid { grid-template-columns: repeat(4, 1fr); }
    .split-section { grid-template-columns: 1fr 1fr; gap: 56px; }
    .split-section.reverse .visual-panel { order: 2; }
    .risk-grid { grid-template-columns: repeat(4, 1fr); }
    .feature-grid, .log-grid, .device-grid, .protocol-grid { grid-template-columns: repeat(3, 1fr); }
    .process-steps { grid-template-columns: repeat(3, 1fr); }
    .article-layout { grid-template-columns: minmax(0, 1fr) 300px; align-items: start; }
    .footer-inner { grid-template-columns: .9fr 1.4fr; }
}
@media (max-width: 480px) {
    .container, .section-inner, .footer-inner, .header-inner, .article-layout { width: min(100% - 24px, 1160px); }
    .section { padding: 56px 0; }
    .download-btn { width: 100%; }
    .hero-actions .download-btn { width: auto; }
    .article-block, .node-card, .feature-card, .risk-card, .faq-item, .log-card, .device-card, .protocol-card, .step-card { padding: 18px; border-radius: 20px; }
}