:root {
    --brand-blue: #2980FE;
    --brand-blue-dark: #1768E8;
    --gradient: linear-gradient(90deg, #3558F2 0%, #7B4EF1 50%, #B84DDA 100%);
    --text: #1F2937;
    --muted: #667085;
    --light: #F5F7FB;
    --lighter: #F8FAFF;
    --border: #E5EAF3;
    --white: #FFFFFF;
    --shadow: 0 18px 50px rgba(26, 42, 92, 0.10);
    --soft-shadow: 0 10px 28px rgba(35, 64, 130, 0.08);
    --radius-lg: 28px;
    --radius-md: 20px;
    --radius-sm: 14px;
}

* {
    box-sizing: border-box;
}

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: var(--white);
    line-height: 1.7;
    overflow-x: hidden;
}

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

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

p {
    margin: 0 0 16px;
}

h1, h2, h3 {
    margin: 0;
    line-height: 1.25;
    color: #111827;
}

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

.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(255, 255, 255, 0.94);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid rgba(229, 234, 243, 0.82);
}

.header-inner {
    min-height: 72px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
}

.logo {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    font-weight: 800;
    color: #13213C;
    letter-spacing: 0.2px;
    white-space: nowrap;
}

.logo img {
    width: 38px;
    height: 38px;
    border-radius: 12px;
    object-fit: cover;
    box-shadow: 0 8px 20px rgba(41, 128, 254, 0.16);
}

.nav-toggle {
    position: absolute;
    opacity: 0;
    pointer-events: none;
}

.nav-toggle-label {
    width: 44px;
    height: 44px;
    border: 1px solid var(--border);
    border-radius: 14px;
    display: grid;
    place-content: center;
    gap: 5px;
    background: var(--white);
    cursor: pointer;
}

.nav-toggle-label span {
    width: 20px;
    height: 2px;
    background: #1F2937;
    border-radius: 99px;
    display: block;
}

.main-nav {
    position: absolute;
    top: 72px;
    left: 16px;
    right: 16px;
    display: none;
    flex-direction: column;
    padding: 12px;
    border: 1px solid var(--border);
    background: var(--white);
    border-radius: 18px;
    box-shadow: var(--soft-shadow);
}

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

.main-nav a {
    padding: 12px 14px;
    color: #344054;
    border-radius: 12px;
    font-size: 15px;
    transition: background .2s ease, color .2s ease;
}

.main-nav a:hover,
.main-nav a.active {
    color: var(--brand-blue);
    background: #EEF5FF;
}

.download-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 48px;
    padding: 12px 24px;
    border-radius: 999px;
    background: var(--brand-blue);
    color: #FFFFFF;
    font-weight: 800;
    letter-spacing: .2px;
    box-shadow: 0 12px 26px rgba(41, 128, 254, .24);
    transition: transform .2s ease, background .2s ease, box-shadow .2s ease;
}

.download-btn:hover {
    background: var(--brand-blue-dark);
    transform: translateY(-2px);
    box-shadow: 0 16px 32px rgba(23, 104, 232, .28);
}

.section {
    padding: 66px 0;
}

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

.section-title {
    text-align: center;
    max-width: 820px;
    margin: 0 auto 34px;
}

.section-title .badge,
.badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 6px 12px;
    margin-bottom: 14px;
    border-radius: 999px;
    color: var(--brand-blue);
    background: #EEF5FF;
    font-size: 13px;
    font-weight: 800;
}

.section-title h2 {
    font-size: clamp(28px, 5vw, 42px);
    margin-bottom: 14px;
}

.section-title p {
    color: var(--muted);
    font-size: 16px;
}

.vpn-network-hero {
    position: relative;
    overflow: hidden;
    background: var(--gradient);
    color: #FFFFFF;
    padding: 70px 0 54px;
}

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

.vpn-network-hero::before {
    width: 420px;
    height: 420px;
    right: -160px;
    top: -120px;
    background: rgba(255, 255, 255, .14);
    filter: blur(8px);
}

.vpn-network-hero::after {
    width: 620px;
    height: 240px;
    left: -200px;
    bottom: -120px;
    background: rgba(255, 255, 255, .13);
    transform: rotate(-8deg);
}

.hero-grid {
    position: relative;
    z-index: 1;
    display: grid;
    gap: 38px;
    align-items: center;
}

.hero-content h1 {
    color: #FFFFFF;
    font-size: clamp(34px, 8vw, 62px);
    letter-spacing: -1px;
    margin-bottom: 18px;
}

.hero-content p {
    color: rgba(255,255,255,.90);
    font-size: 17px;
    max-width: 660px;
}

.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 {
    display: inline-flex;
    align-items: center;
    min-height: 32px;
    padding: 6px 12px;
    border-radius: 999px;
    background: rgba(255,255,255,.16);
    color: #FFFFFF;
    border: 1px solid rgba(255,255,255,.24);
    font-size: 13px;
    font-weight: 700;
}

.hero-visual {
    position: relative;
    min-height: 330px;
    display: grid;
    place-items: center;
}

.node-lines {
    position: absolute;
    inset: 8px;
    border: 1px solid rgba(255,255,255,.18);
    border-radius: 34px;
    background:
        radial-gradient(circle at 18% 26%, rgba(255,255,255,.92) 0 3px, transparent 4px),
        radial-gradient(circle at 68% 18%, rgba(255,255,255,.9) 0 3px, transparent 4px),
        radial-gradient(circle at 84% 62%, rgba(255,255,255,.82) 0 3px, transparent 4px),
        radial-gradient(circle at 34% 78%, rgba(255,255,255,.76) 0 3px, transparent 4px),
        linear-gradient(135deg, rgba(255,255,255,.08), rgba(255,255,255,.02));
}

.hero-device {
    position: relative;
    z-index: 2;
    width: min(360px, 82vw);
    filter: drop-shadow(0 26px 52px rgba(10, 20, 60, .28));
    border-radius: 30px;
}

.float-card {
    position: absolute;
    z-index: 3;
    padding: 10px 14px;
    border-radius: 16px;
    background: rgba(255,255,255,.92);
    color: #173052;
    box-shadow: var(--soft-shadow);
    font-weight: 800;
    font-size: 13px;
}

.float-card.one { left: 4px; top: 54px; }
.float-card.two { right: 6px; top: 112px; }
.float-card.three { left: 18px; bottom: 70px; }
.float-card.four { right: 14px; bottom: 30px; }

.node-overview {
    margin-top: -34px;
    position: relative;
    z-index: 5;
}

.node-overview-grid,
.card-grid,
.risk-grid,
.faq-grid,
.feature-list,
.related-grid {
    display: grid;
    gap: 18px;
}

.node-card,
.info-card,
.risk-card,
.faq-item,
.step-card,
.panel-card,
.tip-box,
.content-card {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 22px;
    box-shadow: var(--soft-shadow);
}

.node-card strong,
.info-card h3,
.risk-card h3,
.faq-item h3,
.step-card h3,
.panel-card h3,
.content-card h3 {
    display: block;
    font-size: 20px;
    margin-bottom: 10px;
    color: #101828;
}

.node-card p,
.info-card p,
.risk-card p,
.step-card p,
.panel-card p,
.content-card p {
    color: var(--muted);
}

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

.split-section {
    display: grid;
    gap: 30px;
    align-items: center;
}

.split-section.reverse .visual-panel {
    order: -1;
}

.copy-block h2 {
    font-size: clamp(28px, 5vw, 42px);
    margin-bottom: 14px;
}

.copy-block p {
    color: var(--muted);
}

.check-list,
.simple-list {
    display: grid;
    gap: 12px;
    margin: 22px 0;
    padding: 0;
    list-style: none;
}

.check-list li,
.simple-list li {
    position: relative;
    padding-left: 28px;
    color: #344054;
}

.check-list li::before,
.simple-list li::before {
    content: "";
    width: 10px;
    height: 10px;
    position: absolute;
    left: 4px;
    top: 10px;
    border-radius: 50%;
    background: var(--brand-blue);
    box-shadow: 0 0 0 5px #EAF3FF;
}

.visual-panel {
    border-radius: var(--radius-lg);
    background: linear-gradient(135deg, #F8FAFF, #EEF5FF);
    border: 1px solid var(--border);
    padding: 22px;
    box-shadow: var(--shadow);
}

.visual-panel img {
    margin: 0 auto;
    border-radius: 24px;
}

.global-nodes-section {
    position: relative;
    overflow: hidden;
    background: #F7FAFF;
}

.global-map-panel {
    position: relative;
    overflow: hidden;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
    padding: 24px;
    background:
        radial-gradient(circle at 22% 32%, rgba(41,128,254,.22) 0 4px, transparent 5px),
        radial-gradient(circle at 62% 24%, rgba(123,78,241,.18) 0 4px, transparent 5px),
        radial-gradient(circle at 78% 64%, rgba(184,77,218,.18) 0 4px, transparent 5px),
        linear-gradient(135deg, #FFFFFF 0%, #EEF5FF 100%);
    box-shadow: var(--shadow);
}

.global-map-panel::before {
    content: "";
    position: absolute;
    inset: 28px;
    border-radius: 24px;
    background: linear-gradient(120deg, transparent 10%, rgba(41,128,254,.16) 11%, transparent 12%, transparent 46%, rgba(123,78,241,.18) 47%, transparent 48%);
    pointer-events: none;
}

.speed-lines {
    display: grid;
    gap: 14px;
    margin-top: 20px;
}

.speed-line {
    padding: 14px;
    border-radius: 16px;
    border: 1px solid var(--border);
    background: #FFFFFF;
}

.speed-line span {
    display: block;
    height: 8px;
    margin-top: 8px;
    border-radius: 99px;
    background: linear-gradient(90deg, #D9E8FF, #2980FE);
}

.privacy-protection-section .panel-card {
    border-left: 4px solid var(--brand-blue);
}

.no-log-policy-section .card-grid,
.encryption-protocol-section .card-grid {
    grid-template-columns: 1fr;
}

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

.step-card {
    position: relative;
}

.step-number {
    width: 38px;
    height: 38px;
    display: inline-grid;
    place-items: center;
    border-radius: 14px;
    background: var(--brand-blue);
    color: #FFFFFF;
    font-weight: 900;
    margin-bottom: 12px;
}

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

.risk-card b {
    color: #1D2939;
}

.faq-item h3 {
    font-size: 18px;
}

.cta-section {
    padding: 68px 0;
    background: var(--gradient);
    color: #FFFFFF;
    text-align: center;
    overflow: hidden;
}

.cta-section h2 {
    color: #FFFFFF;
    font-size: clamp(28px, 5vw, 42px);
    margin-bottom: 14px;
}

.cta-section p {
    color: rgba(255,255,255,.9);
    max-width: 740px;
    margin: 0 auto 24px;
}

.page-hero {
    padding: 56px 0 36px;
    background: linear-gradient(180deg, #F8FAFF 0%, #FFFFFF 100%);
    border-bottom: 1px solid var(--border);
}

.page-hero-inner {
    max-width: 900px;
}

.page-hero h1 {
    font-size: clamp(32px, 6vw, 52px);
    margin-bottom: 16px;
}

.page-hero p {
    color: var(--muted);
    font-size: 17px;
}

.article-layout {
    display: grid;
    gap: 24px;
    align-items: start;
}

.article-main {
    display: grid;
    gap: 20px;
}

.sidebar {
    display: grid;
    gap: 16px;
}

.content-card h2 {
    font-size: 26px;
    margin-bottom: 12px;
}

.content-card p,
.content-card li {
    color: var(--muted);
}

.notice-panel {
    padding: 18px;
    border-radius: 18px;
    border: 1px solid #CFE1FF;
    background: #F0F6FF;
    color: #24518D;
}

.download-page-panel {
    max-width: 860px;
    margin: 0 auto;
    text-align: center;
}

.steps-list {
    display: grid;
    gap: 14px;
    margin: 28px 0;
    text-align: left;
}

.steps-list div {
    display: grid;
    grid-template-columns: 42px 1fr;
    gap: 14px;
    align-items: start;
    padding: 16px;
    border: 1px solid var(--border);
    background: #FFFFFF;
    border-radius: 18px;
}

.steps-list strong {
    width: 42px;
    height: 42px;
    display: grid;
    place-items: center;
    border-radius: 14px;
    color: #FFFFFF;
    background: var(--brand-blue);
}

.site-footer {
    background: #F2F5FA;
    border-top: 1px solid var(--border);
    padding-top: 48px;
}

.footer-grid {
    display: grid;
    gap: 26px;
}

.footer-brand p {
    color: var(--muted);
    margin-top: 16px;
}

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

.site-footer a:not(.logo) {
    display: block;
    color: #667085;
    margin: 8px 0;
}

.site-footer a:hover {
    color: var(--brand-blue);
}

.footer-bottom {
    margin-top: 34px;
    padding: 18px 0;
    border-top: 1px solid var(--border);
    color: #667085;
    font-size: 14px;
}

@media (min-width: 640px) {
    .node-overview-grid,
    .card-grid,
    .risk-grid,
    .faq-grid,
    .related-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .process-steps {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
}

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

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

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

    .hero-grid,
    .split-section {
        grid-template-columns: 1.03fr .97fr;
    }

    .split-section.reverse .visual-panel {
        order: initial;
    }

    .node-overview-grid {
        grid-template-columns: repeat(4, minmax(0, 1fr));
    }

    .card-grid.three,
    .risk-grid {
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }

    .no-log-policy-section .card-grid,
    .encryption-protocol-section .card-grid {
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }

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

    .footer-grid {
        grid-template-columns: 1.4fr repeat(3, 1fr);
    }
}

@media (min-width: 1120px) {
    .main-nav a {
        padding: 10px 13px;
        font-size: 15px;
    }

    .process-steps {
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }
}

@media (max-width: 420px) {
    .container {
        width: min(100% - 24px, 1180px);
    }

    .site-header .logo span {
        font-size: 15px;
    }

    .section {
        padding: 52px 0;
    }

    .hero-visual {
        min-height: 280px;
    }

    .float-card {
        font-size: 12px;
        padding: 8px 10px;
    }

    .download-btn {
        width: 100%;
    }
}