:root {
        --bg: #ffffff;
        --fg: #1a1a1a;
        --border: rgba(26, 26, 26, 0.18);
        --muted: rgba(26, 26, 26, 0.72);

        --font-zh: "Source Han Serif SC", "Noto Serif SC", "Songti SC", serif;
        --font-en: Georgia, "Times New Roman", serif;
        --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono",
          "Courier New", monospace;
      }

      * {
        box-sizing: border-box;
      }

      html {
        scroll-behavior: smooth;
        background: var(--bg);
        color: var(--fg);
      }

      body {
        margin: 0;
        background: var(--bg);
        color: var(--fg);
        min-height: 100vh;
      }

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

      a:focus-visible,
      button:focus-visible {
        outline: 2px solid var(--fg);
        outline-offset: 3px;
      }

      /* Top language switch */
      .topbar {
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        z-index: 20;
        display: flex;
        justify-content: center;
        padding: 14px 16px;
        pointer-events: none;
      }

      .topbar-inner {
        pointer-events: auto;
        width: min(760px, 100%);
        display: flex;
        justify-content: flex-end;
      }

      .lang-switch {
        display: inline-flex;
        align-items: center;
        border: 1px solid var(--border);
        border-radius: 999px;
        overflow: hidden;
        background: rgba(255, 255, 255, 0.92);
        backdrop-filter: blur(2px);
      }

      .lang-switch button {
        appearance: none;
        border: 0;
        background: transparent;
        color: var(--fg);
        padding: 10px 14px;
        font: inherit;
        font-size: 14px;
        cursor: pointer;
      }

      .lang-switch button[aria-pressed="true"] {
        background: var(--fg);
        color: var(--bg);
      }

      /* Layout */
      .container {
        width: min(980px, 100%);
        margin: 0 auto;
        padding: 0 18px;
      }

      .section {
        padding: 96px 0;
      }

      .section-title {
        font-weight: 600;
        margin: 0 0 22px;
        font-size: clamp(22px, 2.4vw, 32px);
        line-height: 1.2;
      }

      .copy {
        max-width: 72ch;
        font-size: clamp(15px, 1.6vw, 18px);
        line-height: 1.85;
        margin: 0;
        color: var(--fg);
      }

      .muted {
        color: var(--muted);
      }

      /* Hero */
      .hero {
        min-height: 100vh;
        display: grid;
        place-items: center;
        padding-top: 72px;
        position: relative;
        overflow: hidden;
      }

      .hero-canvas {
        position: absolute;
        inset: 0;
        width: 100%;
        height: 100%;
        pointer-events: none;
        opacity: 0.72;
        z-index: 0;
      }

      .hero-inner {
        text-align: center;
        padding: 0 10px;
        position: relative;
        z-index: 1;
      }

      .hero-logo {
        width: clamp(62px, 8vw, 94px);
        height: clamp(62px, 8vw, 94px);
        border-radius: 50%;
        object-fit: cover;
        display: block;
        margin: 0 auto 18px;
        border: 1px solid rgba(26, 26, 26, 0.18);
        background: #fff;
      }

      .hero-titles {
        display: flex;
        flex-direction: column;
        align-items: center;
        gap: 14px;
        margin-bottom: 22px;
      }

      .hero-title {
        font-weight: 600;
        letter-spacing: -0.01em;
        line-height: 1.12;
        opacity: 1;
      }

      .hero-title[data-lang="zh"] {
        font-family: var(--font-zh);
        font-size: clamp(40px, 6vw, 72px);
      }

      .hero-title[data-lang="en"] {
        font-family: var(--font-en);
        font-size: clamp(34px, 5.2vw, 64px);
      }

      /* Order swap */
      body[data-lang="en"] .hero-title[data-lang="zh"] {
        order: 2;
      }
      body[data-lang="en"] .hero-title[data-lang="en"] {
        order: 1;
      }

      body[data-lang="zh"] .hero-title[data-lang="en"] {
        order: 2;
      }

      body[data-lang="zh"] .hero-title[data-lang="en"] {
        opacity: 0.55;
      }

      body[data-lang="en"] .hero-title[data-lang="zh"] {
        opacity: 0.55;
      }

      .version {
        font-size: 14px;
        letter-spacing: 0.06em;
        margin: 10px 0 16px;
      }

      .slogan {
        margin: 0;
        font-size: clamp(16px, 2vw, 20px);
        line-height: 1.7;
      }

      .slogan-line {
        font-weight: 500;
      }

      .scroll-arrow {
        display: inline-block;
        margin-top: 34px;
        font-size: 22px;
        padding: 10px 14px;
        border-radius: 999px;
        border: 1px solid var(--border);
        color: var(--fg);
        background: rgba(255, 255, 255, 0.7);
      }

      .scroll-arrow:active {
        transform: translateY(1px);
      }

      /* File tree */
      .tree {
        margin-top: 10px;
        font-family: var(--font-mono);
        font-size: 14px;
        line-height: 1.75;
        max-width: 60ch;
      }

      .tree-line {
        display: flex;
        align-items: baseline;
        gap: 10px;
        padding: 2px 0;
      }

      .tree-prefix {
        min-width: 22px;
        color: var(--muted);
      }

      .download-link {
        display: inline-block;
        border-bottom: 1px solid transparent;
        padding-bottom: 2px;
      }

      .download-link:hover {
        border-bottom-color: var(--fg);
      }

      /* Footer */
      footer {
        padding: 56px 0 72px;
        border-top: 1px solid var(--border);
      }

      .footer-grid {
        display: grid;
        grid-template-columns: 1fr;
        gap: 14px;
      }

      .footer-line {
        font-size: 14px;
        line-height: 1.7;
      }

      .footer-links a {
        border-bottom: 1px solid transparent;
      }

      .footer-links a:hover {
        border-bottom-color: var(--fg);
      }

      @media (max-width: 520px) {
        .topbar-inner {
          justify-content: center;
        }

        .lang-switch button {
          font-size: 13px;
          padding: 9px 12px;
        }

        .section {
          padding: 72px 0;
        }

        .copy {
          line-height: 1.8;
        }
      }

.collab-closing {
  margin-top: 18px;
}

#paper-links .paper-links-body {
  font-size: 15px;
  line-height: 2;
}

.noscript-banner {
  padding: 12px 18px;
  font-size: 14px;
  line-height: 1.6;
  border-bottom: 1px solid rgba(26, 26, 26, 0.18);
}