:root {
    --bg: #05070c;
    --bg-soft: #0b1120;
    --panel: #101a2f;
    --text: #f2f5ff;
    --text-dim: #b8c0d4;
    --accent: #3ae6b2;
    --accent-strong: #18b88a;
    --line: rgba(255, 255, 255, 0.12);
    --shadow: 0 20px 60px rgba(0, 0, 0, 0.45);
}

html {
    scroll-behavior: smooth;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    color: var(--text);
    font-family: "Noto Sans SC", sans-serif;
    background:
        radial-gradient(1200px 500px at 80% -10%, rgba(58, 230, 178, 0.26), transparent 60%),
        radial-gradient(900px 480px at -10% 10%, rgba(67, 135, 255, 0.2), transparent 50%),
        var(--bg);
    line-height: 1.65;
}

h1,
h2,
h3,
.brand-name,
.tag {
    font-family: "Space Grotesk", "Noto Sans SC", sans-serif;
    letter-spacing: 0.01em;
}

.topbar {
    position: sticky;
    top: 0;
    z-index: 10;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    padding: 14px 6vw;
    backdrop-filter: blur(10px);
    background: rgba(5, 7, 12, 0.74);
    border-bottom: 1px solid var(--line);
}

.top-actions {
    display: inline-flex;
    align-items: center;
    gap: 10px;
}

.brand {
    color: var(--text);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 10px;
}

.brand-mark {
    width: 32px;
    height: 32px;
    border-radius: 9px;
    display: grid;
    place-items: center;
    font-size: 13px;
    font-weight: 700;
    color: #00190f;
    background: linear-gradient(130deg, var(--accent), #8be3ff);
}

.brand-name {
    font-size: 1.05rem;
    font-weight: 700;
}

.nav {
    display: flex;
    gap: 18px;
}

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

.nav a:hover {
    color: var(--text);
}

.lang-toggle {
    display: inline-flex;
    border: 1px solid var(--line);
    border-radius: 11px;
    overflow: hidden;
    background: rgba(255, 255, 255, 0.02);
}

.lang-btn {
    border: 0;
    color: var(--text-dim);
    background: transparent;
    padding: 7px 10px;
    font-size: 0.82rem;
    cursor: pointer;
}

.lang-btn.is-active {
    color: #031209;
    background: linear-gradient(130deg, var(--accent), #6ecfff);
}

.btn {
    border-radius: 12px;
    border: 1px solid transparent;
    padding: 9px 15px;
    text-decoration: none;
    color: var(--text);
    font-size: 0.92rem;
    font-weight: 500;
    transition: transform 0.2s ease, border-color 0.2s ease, background 0.2s ease;
}

.btn:hover {
    transform: translateY(-1px);
}

.btn-primary {
    background: linear-gradient(130deg, var(--accent), #6ecfff);
    color: #031209;
}

.btn-ghost {
    border-color: var(--line);
    background: rgba(255, 255, 255, 0.02);
}

main {
    width: min(1100px, 92vw);
    margin: 0 auto;
    padding-bottom: 56px;
}

.hero {
    padding: 84px 0 58px;
}

.tag {
    color: var(--accent);
    text-transform: uppercase;
    font-size: 0.8rem;
    font-weight: 700;
    margin-bottom: 14px;
}

h1 {
    font-size: clamp(2rem, 6vw, 4rem);
    line-height: 1.08;
    margin: 0;
}

.hero-desc {
    width: min(700px, 100%);
    color: var(--text-dim);
    margin-top: 18px;
}

.hero-cta {
    margin-top: 24px;
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

.hero-meta {
    margin-top: 30px;
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 12px;
}

.hero-meta div {
    border: 1px solid var(--line);
    background: rgba(255, 255, 255, 0.02);
    border-radius: 14px;
    padding: 14px;
}

.hero-meta strong {
    font-size: 1.02rem;
    display: block;
}

.hero-meta span {
    color: var(--text-dim);
    font-size: 0.9rem;
}

.section {
    margin-top: 26px;
    padding: 30px;
    border-radius: 22px;
    border: 1px solid var(--line);
    background: linear-gradient(160deg, rgba(255, 255, 255, 0.04), rgba(255, 255, 255, 0.01));
    box-shadow: var(--shadow);
}

.ai-section {
    border-color: rgba(58, 230, 178, 0.45);
    background:
        radial-gradient(700px 280px at 100% -10%, rgba(58, 230, 178, 0.18), transparent 65%),
        linear-gradient(160deg, rgba(255, 255, 255, 0.04), rgba(255, 255, 255, 0.01));
}

.ai-grid {
    margin-top: 18px;
    display: grid;
    gap: 12px;
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.ai-panel {
    border: 1px solid rgba(58, 230, 178, 0.35);
    border-radius: 16px;
    padding: 16px;
    background: rgba(58, 230, 178, 0.06);
}

.ai-panel h3 {
    margin: 0;
}

.ai-panel p {
    margin: 8px 0 0;
    color: #d8ffe8;
}

.section-head p {
    margin: 0;
    color: var(--accent);
    font-size: 0.85rem;
    text-transform: uppercase;
}

.section-head h2 {
    margin: 6px 0 0;
    font-size: clamp(1.4rem, 3vw, 2.2rem);
}

.grid {
    margin-top: 20px;
    display: grid;
    gap: 14px;
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.card {
    border: 1px solid var(--line);
    border-radius: 16px;
    padding: 18px;
    background: rgba(4, 8, 17, 0.52);
}

.card h3 {
    margin: 0;
    font-size: 1.05rem;
}

.card p {
    margin: 8px 0 0;
    color: var(--text-dim);
}

.rule-list {
    margin-top: 18px;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.rule-list span {
    border: 1px solid var(--line);
    background: rgba(58, 230, 178, 0.08);
    color: #d7ffef;
    padding: 8px 12px;
    border-radius: 999px;
    font-size: 0.88rem;
}

.timeline {
    margin: 16px 0 0;
    padding-left: 22px;
    color: var(--text-dim);
}

.timeline li + li {
    margin-top: 9px;
}

.code-block {
    margin: 18px 0 0;
    border-radius: 16px;
    border: 1px solid rgba(139, 227, 255, 0.28);
    background: linear-gradient(180deg, #091225, #060b16);
    padding: 16px;
    overflow-x: auto;
    color: #d7ebff;
}

.code-block code {
    font-family: "SFMono-Regular", "Consolas", "Liberation Mono", monospace;
    font-size: 0.9rem;
}

.footer {
    width: min(1100px, 92vw);
    margin: 0 auto 30px;
    padding-top: 10px;
    border-top: 1px solid var(--line);
    display: flex;
    justify-content: space-between;
    gap: 10px;
    color: var(--text-dim);
}

.footer a {
    color: var(--text-dim);
    text-decoration: none;
}

.reveal {
    opacity: 0;
    transform: translateY(16px);
    transition: opacity 0.5s ease, transform 0.5s ease;
}

.reveal.in {
    opacity: 1;
    transform: translateY(0);
}

@media (max-width: 860px) {
    .topbar {
        flex-wrap: wrap;
        justify-content: center;
    }

    .nav {
        order: 3;
        width: 100%;
        justify-content: center;
        padding-bottom: 4px;
        flex-wrap: wrap;
    }

    .top-actions {
        width: 100%;
        justify-content: center;
    }

    .hero-meta {
        grid-template-columns: 1fr;
    }

    .ai-grid,
    .grid {
        grid-template-columns: 1fr;
    }

    .section {
        padding: 22px;
        border-radius: 18px;
    }
}