:root {
    --bg: #0b1220;
    --bg-soft: #111b2e;
    --surface: rgba(16, 27, 44, 0.72);
    --surface-border: rgba(124, 154, 196, 0.25);
    --text: #ecf3ff;
    --muted: #b3c5df;
    --accent: #3ddc97;
    --accent-2: #49a8ff;
    --danger: #ff6f61;
    --max-width: 960px;
    --radius: 20px;
    --shadow: 0 20px 60px rgba(0, 0, 0, 0.35);
}

* {
    box-sizing: border-box;
}

html,
body {
    margin: 0;
    padding: 0;
}

body {
    font-family: "Space Grotesk", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    color: var(--text);
    background:
        radial-gradient(circle at 10% 10%, rgba(73, 168, 255, 0.24), transparent 40%),
        radial-gradient(circle at 90% 20%, rgba(61, 220, 151, 0.18), transparent 35%),
        linear-gradient(145deg, #080d18 0%, #0f1b2f 100%);
    min-height: 100vh;
    line-height: 1.65;
}

.mesh {
    position: fixed;
    inset: 0;
    z-index: -1;
    pointer-events: none;
    background-image: linear-gradient(to right, rgba(125, 154, 193, 0.07) 1px, transparent 1px),
        linear-gradient(to bottom, rgba(125, 154, 193, 0.07) 1px, transparent 1px);
    background-size: 42px 42px;
    mask-image: radial-gradient(circle at center, black 30%, transparent 90%);
}

.shell {
    width: min(var(--max-width), 92vw);
    margin: 0 auto;
    padding: 24px 0 72px;
}

.topbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    margin-bottom: 24px;
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    color: var(--text);
    text-decoration: none;
    font-weight: 700;
    letter-spacing: 0.4px;
}

.brand-mark {
    width: 34px;
    height: 34px;
    border-radius: 10px;
    background: linear-gradient(135deg, var(--accent), var(--accent-2));
    box-shadow: 0 8px 24px rgba(73, 168, 255, 0.45);
    display: grid;
    place-items: center;
    color: #04253b;
    font-weight: 800;
}

.topnav {
    display: inline-flex;
    align-items: center;
    gap: 14px;
    flex-wrap: wrap;
    justify-content: center;
}

.topnav a {
    color: var(--muted);
    text-decoration: none;
    font-size: 0.94rem;
}

.topnav a[aria-current="page"] {
    color: var(--text);
    font-weight: 700;
}

.lang-switch {
    display: inline-flex;
    border: 1px solid var(--surface-border);
    border-radius: 999px;
    padding: 4px;
    background: rgba(8, 14, 26, 0.55);
}

.lang-btn {
    border: 0;
    color: var(--muted);
    background: transparent;
    border-radius: 999px;
    padding: 6px 12px;
    font: inherit;
    cursor: pointer;
}

.lang-btn.active {
    color: #022013;
    background: linear-gradient(120deg, var(--accent), #7ef0bd);
    font-weight: 700;
}

.card {
    background: var(--surface);
    border: 1px solid var(--surface-border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    backdrop-filter: blur(8px);
    padding: 26px;
    margin-bottom: 18px;
}

h1,
h2,
h3 {
    line-height: 1.2;
    margin: 0 0 12px;
}

h1 {
    font-size: clamp(1.7rem, 2.8vw, 2.35rem);
}

h2 {
    font-size: clamp(1.2rem, 2.2vw, 1.55rem);
    margin-top: 6px;
}

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

ul {
    margin: 0;
    padding-left: 20px;
}

.lead {
    color: #d9e8fb;
    max-width: 70ch;
}

.eyebrow {
    margin: 0 0 10px;
    color: #8bd7b4;
    font-size: 0.84rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    font-weight: 700;
}

.meta {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 14px;
}

.chip {
    font-size: 0.86rem;
    color: #cde4ff;
    border: 1px solid rgba(123, 167, 224, 0.32);
    background: rgba(55, 100, 154, 0.22);
    padding: 5px 10px;
    border-radius: 999px;
}

.chip.warning {
    border-color: rgba(255, 145, 134, 0.4);
    background: rgba(160, 56, 48, 0.24);
    color: #ffd7d3;
}

.nav-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px;
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 12px;
    margin-bottom: 18px;
}

.feature-card {
    border-radius: 16px;
    border: 1px solid var(--surface-border);
    background: linear-gradient(160deg, rgba(19, 33, 55, 0.82), rgba(14, 24, 39, 0.72));
    padding: 18px;
    box-shadow: var(--shadow);
}

.feature-title {
    font-weight: 700;
    margin-bottom: 8px;
}

.nav-card {
    border-radius: 16px;
    border: 1px solid var(--surface-border);
    background: linear-gradient(160deg, rgba(19, 33, 55, 0.85), rgba(14, 24, 39, 0.76));
    color: var(--text);
    padding: 16px;
    text-decoration: none;
    transition: transform 0.2s ease, border-color 0.2s ease;
}

.nav-card:hover {
    transform: translateY(-2px);
    border-color: rgba(126, 240, 189, 0.44);
}

.nav-title {
    font-weight: 700;
    margin-bottom: 6px;
}

.footer {
    margin-top: 16px;
    color: #aac0df;
    font-size: 0.92rem;
}

.split {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 18px;
    align-items: center;
}

.hero-split {
    align-items: start;
}

.hero-actions,
.link-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
    min-width: 180px;
}

.cta-primary,
.cta-secondary,
.link-list a {
    border-radius: 14px;
    padding: 12px 14px;
    text-decoration: none;
    text-align: center;
    font-weight: 700;
}

.cta-primary {
    background: linear-gradient(135deg, var(--accent), #7ef0bd);
    color: #03231b;
}

.cta-secondary,
.link-list a {
    background: rgba(34, 56, 88, 0.45);
    border: 1px solid var(--surface-border);
    color: var(--text);
}

a {
    color: #8cc8ff;
}

.lang {
    display: none;
}

html[data-lang="en"] .lang.en,
html[data-lang="zh"] .lang.zh {
    display: block;
}

html[data-lang="en"] .lang.en.inline,
html[data-lang="zh"] .lang.zh.inline {
    display: inline;
}

.steps {
    padding-left: 20px;
}

.steps li {
    margin-bottom: 8px;
}

@media (max-width: 820px) {
    .topbar {
        flex-direction: column;
        align-items: stretch;
    }

    .topnav {
        justify-content: flex-start;
    }

    .nav-grid {
        grid-template-columns: 1fr;
    }

    .feature-grid {
        grid-template-columns: 1fr;
    }

    .split {
        grid-template-columns: 1fr;
    }

    .hero-actions,
    .link-list {
        min-width: 0;
    }

    .shell {
        padding-bottom: 44px;
    }

    .card {
        padding: 20px;
    }
}