:root {
    --bg: #f8fafc;
    --panel: rgba(255,255,255,.82);
    --ink: #0f172a;
    --muted: #64748b;
    --line: rgba(15,23,42,.10);
    --soft: rgba(15,23,42,.05);
    --accent: #111827;
    --accent-2: #475569;
    --radius: 28px;
    --shadow: 0 24px 80px rgba(15,23,42,.08);
    --shadow-soft: 0 16px 40px rgba(15,23,42,.06);
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
    color: var(--ink);
    background:
        radial-gradient(circle at 12% 8%, rgba(148,163,184,.22), transparent 28%),
        radial-gradient(circle at 86% 0%, rgba(15,23,42,.10), transparent 24%),
        var(--bg);
    line-height: 1.75;
}

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

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

button,
input,
textarea {
    font: inherit;
}

.container {
    width: min(1180px, calc(100% - 40px));
    margin-inline: auto;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    clip: rect(0,0,0,0);
    overflow: hidden;
    white-space: nowrap;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 30;
    padding: 14px 0 16px;
    backdrop-filter: blur(22px);
    background: rgba(248,250,252,.82);
    border-bottom: 1px solid var(--line);
}

.header-inner {
    display: flex;
    align-items: center;
    gap: 22px;
    justify-content: space-between;
}

.brand-logo {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    min-width: max-content;
}

.brand-logo img {
    border-radius: 16px;
    box-shadow: var(--shadow-soft);
}

.brand-logo strong {
    display: block;
    font-size: 1.05rem;
    letter-spacing: .04em;
}

.brand-logo small {
    display: block;
    color: var(--muted);
    font-size: .74rem;
    line-height: 1.1;
}

.main-nav {
    display: flex;
    gap: 8px;
    padding: 6px;
    border: 1px solid var(--line);
    border-radius: 999px;
    background: rgba(255,255,255,.72);
    overflow-x: auto;
    scrollbar-width: none;
}

.main-nav::-webkit-scrollbar {
    display: none;
}

.main-nav a {
    padding: 8px 14px;
    color: #475569;
    border-radius: 999px;
    white-space: nowrap;
    transition: background .22s ease, color .22s ease, transform .22s ease;
}

.main-nav a:hover,
.main-nav a.is-active {
    color: var(--ink);
    background: rgba(15,23,42,.08);
    transform: translateY(-1px);
}

.header-cta,
.btn-primary,
.btn-secondary,
.search-form button {
    border: 0;
    border-radius: 999px;
    padding: 11px 18px;
    background: var(--accent);
    color: #fff;
    cursor: pointer;
    box-shadow: 0 14px 36px rgba(15,23,42,.18);
    transition: transform .22s ease, box-shadow .22s ease, background .22s ease;
}

.header-cta:hover,
.btn-primary:hover,
.btn-secondary:hover,
.search-form button:hover {
    transform: translateY(-2px);
    box-shadow: 0 20px 44px rgba(15,23,42,.22);
}

.search-panel {
    margin-top: 14px;
}

.search-form {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 10px;
    padding: 8px;
    border: 1px solid var(--line);
    border-radius: 24px;
    background: rgba(255,255,255,.74);
}

.search-form input {
    border: 0;
    background: transparent;
    outline: 0;
    padding: 11px 16px;
    color: var(--ink);
}

.search-hint {
    margin: 8px 8px 0;
    color: var(--muted);
    font-size: .9rem;
}

main {
    overflow: hidden;
}

.hero {
    padding: 86px 0 42px;
}

.hero-grid {
    display: grid;
    grid-template-columns: minmax(0, 1.04fr) minmax(320px, .8fr);
    gap: 38px;
    align-items: center;
}

.eyebrow {
    display: inline-flex;
    gap: 8px;
    align-items: center;
    margin: 0 0 18px;
    color: #334155;
    background: rgba(255,255,255,.72);
    border: 1px solid var(--line);
    border-radius: 999px;
    padding: 7px 12px;
    font-size: .9rem;
}

h1,
h2,
h3 {
    letter-spacing: -.04em;
    line-height: 1.12;
}

h1 {
    margin: 0;
    font-size: clamp(2.5rem, 7vw, 5.9rem);
}

h2 {
    margin: 0 0 14px;
    font-size: clamp(2rem, 4vw, 3.6rem);
}

h3 {
    margin: 0 0 10px;
    font-size: 1.24rem;
}

.lead {
    margin: 22px 0 0;
    max-width: 720px;
    font-size: clamp(1rem, 1.7vw, 1.24rem);
    color: #475569;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 14px;
    margin-top: 30px;
}

.btn-secondary {
    background: rgba(255,255,255,.82);
    color: var(--ink);
    border: 1px solid var(--line);
    box-shadow: var(--shadow-soft);
}

.hero-card,
.panel,
.topic-card,
.board-card,
.review-card,
.faq-card,
.join-card,
.rank-card,
.inner-card {
    border: 1px solid var(--line);
    border-radius: var(--radius);
    background: var(--panel);
    box-shadow: var(--shadow-soft);
}

.hero-card {
    position: relative;
    overflow: hidden;
    padding: 18px;
    min-height: 520px;
}

.hero-card::after {
    content: "";
    position: absolute;
    inset: auto -90px -100px auto;
    width: 260px;
    height: 260px;
    background: rgba(15,23,42,.08);
    border-radius: 999px;
}

.hero-card img {
    height: 330px;
    width: 100%;
    object-fit: cover;
    border-radius: 24px;
}

.hero-card-body {
    position: relative;
    padding: 22px 8px 4px;
}

.metric-row {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    margin-top: 18px;
}

.metric {
    padding: 14px;
    border-radius: 18px;
    background: rgba(15,23,42,.04);
}

.metric strong {
    display: block;
    font-size: 1.3rem;
}

.metric span {
    color: var(--muted);
    font-size: .88rem;
}

.section {
    padding: 74px 0;
}

.section-head {
    display: flex;
    justify-content: space-between;
    align-items: end;
    gap: 24px;
    margin-bottom: 26px;
}

.section-head p {
    max-width: 620px;
    margin: 0;
    color: var(--muted);
}

.panel {
    padding: clamp(24px, 4vw, 46px);
}

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

.intro-grid p {
    margin: 0;
    color: #475569;
}

.topic-grid,
.board-grid,
.review-grid,
.inner-grid {
    display: grid;
    gap: 18px;
}

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

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

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

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

.topic-card,
.board-card,
.review-card,
.inner-card,
.rank-card {
    overflow: hidden;
    transition: transform .24s ease, box-shadow .24s ease, border-color .24s ease;
}

.topic-card:hover,
.board-card:hover,
.review-card:hover,
.inner-card:hover,
.rank-card:hover {
    transform: translateY(-6px);
    border-color: rgba(15,23,42,.18);
    box-shadow: var(--shadow);
}

.video-frame {
    position: relative;
    aspect-ratio: 16 / 9;
    overflow: hidden;
    background: #e2e8f0;
}

.video-frame img,
.video-frame video {
    width: 100%;
    height: 100%;
    object-fit: cover;
    filter: saturate(.96);
    transition: transform .4s ease, filter .4s ease;
}

.topic-card:hover .video-frame img,
.topic-card:hover .video-frame video {
    transform: scale(1.035);
    filter: saturate(1.04);
}

.play-button {
    position: absolute;
    inset: 50% auto auto 50%;
    transform: translate(-50%, -50%) scale(.88);
    display: grid;
    place-items: center;
    width: 68px;
    height: 68px;
    border: 1px solid rgba(255,255,255,.72);
    border-radius: 999px;
    color: #fff;
    background: rgba(15,23,42,.46);
    backdrop-filter: blur(10px);
    opacity: 0;
    transition: opacity .22s ease, transform .22s ease;
}

.play-button::before {
    content: "";
    margin-left: 4px;
    border-style: solid;
    border-width: 13px 0 13px 20px;
    border-color: transparent transparent transparent #fff;
}

.topic-card:hover .play-button,
.topic-card.is-playing .play-button {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1);
}

.card-body {
    padding: 20px;
}

.card-body p {
    color: var(--muted);
    margin: 0 0 14px;
}

.tags {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.tag {
    font-size: .78rem;
    padding: 5px 9px;
    border-radius: 999px;
    background: rgba(15,23,42,.06);
    color: #334155;
}

.stats-line {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    color: #64748b;
    font-size: .86rem;
    margin-top: 14px;
}

.board-card {
    padding: 24px;
}

.board-card .icon {
    display: grid;
    place-items: center;
    width: 42px;
    height: 42px;
    border-radius: 16px;
    background: rgba(15,23,42,.07);
    margin-bottom: 22px;
}

.stats-band {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 18px;
}

.stats-band .metric {
    padding: 28px;
    border: 1px solid var(--line);
    background: rgba(255,255,255,.76);
    border-radius: 26px;
}

.stats-band strong {
    font-size: clamp(1.8rem, 4vw, 3.3rem);
    letter-spacing: -.06em;
}

.review-card {
    padding: 24px;
}

.review-card blockquote {
    margin: 0;
    color: #334155;
}

.review-card cite {
    display: block;
    margin-top: 18px;
    color: var(--muted);
    font-style: normal;
}

.faq-list {
    display: grid;
    gap: 12px;
}

.faq-card {
    padding: 0;
}

.faq-card summary {
    cursor: pointer;
    list-style: none;
    padding: 22px 24px;
    font-weight: 700;
}

.faq-card summary::-webkit-details-marker {
    display: none;
}

.faq-card p {
    margin: 0;
    padding: 0 24px 24px;
    color: var(--muted);
}

.join-card {
    display: grid;
    grid-template-columns: 1fr .78fr;
    gap: 28px;
    padding: clamp(24px, 4vw, 42px);
    align-items: center;
}

.join-form {
    display: grid;
    gap: 12px;
}

.join-form input,
.join-form textarea {
    width: 100%;
    border: 1px solid var(--line);
    border-radius: 18px;
    padding: 14px 16px;
    outline: 0;
    background: rgba(255,255,255,.68);
}

.site-footer {
    padding: 52px 0;
    border-top: 1px solid var(--line);
    background: rgba(255,255,255,.58);
}

.footer-grid {
    display: grid;
    grid-template-columns: 1.3fr .7fr 1fr;
    gap: 30px;
    align-items: start;
}

.footer-copy,
.footer-meta {
    color: var(--muted);
}

.site-footer nav {
    display: grid;
    gap: 10px;
}

.site-footer nav a {
    color: #334155;
}

.toast {
    position: fixed;
    left: 50%;
    bottom: 28px;
    z-index: 50;
    transform: translateX(-50%) translateY(20px);
    opacity: 0;
    pointer-events: none;
    padding: 12px 18px;
    border-radius: 999px;
    background: #0f172a;
    color: #fff;
    box-shadow: var(--shadow);
    transition: opacity .2s ease, transform .2s ease;
}

.toast.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

.breadcrumb {
    margin: 34px 0 -34px;
    color: var(--muted);
    font-size: .95rem;
}

.inner-hero {
    padding: 76px 0 34px;
}

.rank-list {
    display: grid;
    gap: 14px;
}

.rank-card {
    display: grid;
    grid-template-columns: auto 1fr auto;
    gap: 16px;
    align-items: center;
    padding: 18px;
}

.rank-no {
    display: grid;
    place-items: center;
    width: 42px;
    height: 42px;
    border-radius: 16px;
    background: rgba(15,23,42,.08);
    font-weight: 800;
}

.notice {
    padding: 16px 18px;
    border: 1px solid var(--line);
    border-radius: 20px;
    color: var(--muted);
    background: rgba(255,255,255,.74);
}

@media (max-width: 980px) {
    .header-inner {
        flex-wrap: wrap;
    }

    .main-nav {
        order: 3;
        width: 100%;
    }

    .hero-grid,
    .join-card,
    .footer-grid,
    .intro-grid {
        grid-template-columns: 1fr;
    }

    .topic-grid,
    .review-grid,
    .inner-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .board-grid,
    .stats-band {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .hero-card {
        min-height: 0;
    }
}

@media (max-width: 640px) {
    .container {
        width: min(100% - 28px, 1180px);
    }

    .header-cta {
        display: none;
    }

    .search-form {
        grid-template-columns: 1fr;
    }

    .hero {
        padding-top: 48px;
    }

    .section {
        padding: 48px 0;
    }

    .section-head {
        display: block;
    }

    .topic-grid,
    .board-grid,
    .review-grid,
    .inner-grid,
    .stats-band {
        grid-template-columns: 1fr;
    }

    .metric-row {
        grid-template-columns: 1fr;
    }

    .rank-card {
        grid-template-columns: auto 1fr;
    }

    .rank-card .stats-line {
        grid-column: 1 / -1;
    }
}

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        scroll-behavior: auto !important;
        transition-duration: .01ms !important;
        animation-duration: .01ms !important;
    }
}