@font-face { font-family: basel; src: url("https://arena.ai/cms/_next/static/media/Basel_Grotesk_Regular-s.p.fb5bf91c.woff2") format("woff2"); font-display: swap; font-weight: 400; }
@font-face { font-family: basel; src: url("https://arena.ai/cms/_next/static/media/Basel_Grotesk_Medium-s.p.0be5fa49.woff2") format("woff2"); font-display: swap; font-weight: 500; }
@font-face { font-family: martina; src: url("https://arena.ai/cms/_next/static/media/martina_plantijn_light-s.p.5b8c085b.woff2") format("woff2"); font-display: swap; font-weight: 300; }
:root { color-scheme: light; --paper: #fcfaf7; --ink: #1a1919; --muted: #6f6a65; --line: #d8d3cc; --wash: #f1eee9; --accent: #1a1919; --article-width: 845px; --rail-width: 220px; }
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 120px; }
body.research-page { margin: 0; background: var(--paper); color: var(--ink); font: 16px/1.5 basel, "Arial", sans-serif; }
a { color: inherit; text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }
.skip-link { position: fixed; z-index: 20; inset: 8px auto auto 8px; transform: translateY(-160%); padding: 10px 14px; background: white; }
.skip-link:focus { transform: none; }
.research-header { position: sticky; z-index: 10; top: 0; display: flex; align-items: flex-end; justify-content: space-between; width: min(1280px, calc(100% - 160px)); height: 64px; margin: 47px auto 0; padding-bottom: 12px; border-bottom: 1px solid var(--ink); background: var(--paper); }
.brand { display: inline-flex; align-items: baseline; gap: 5px; font: 26px/1 martina, Georgia, serif; text-decoration: none; }
.brand img { display: block; width: 79px; height: auto; }
.brand span { font: 24px/1 martina, Georgia, serif; }
.header-action { display: inline-flex; gap: 8px; align-items: center; border: 0; padding: 0; color: inherit; background: transparent; font: 12px/1.2 basel, Arial, sans-serif; cursor: pointer; }
.menu-square { width: 10px; height: 10px; background: currentColor; }
.research-menu { position: absolute; right: 0; top: 100%; display: grid; gap: 16px; min-width: 220px; padding: 24px; background: var(--paper); border: 1px solid var(--line); font-size: 14px; }
.research-menu[hidden] { display: none; }
.research-menu a { text-decoration: none; }
.research-layout { display: grid; grid-template-columns: minmax(0, var(--article-width)) minmax(180px, var(--rail-width)); align-items: start; justify-content: space-between; gap: 55px; width: min(1280px, calc(100% - 160px)); margin: 110px auto 140px; }
.research-article { min-width: 0; }
.cover { width: 100%; aspect-ratio: 169 / 95; margin: 0 0 64px; overflow: hidden; border-radius: 8px; background: #292625; }
.cover img { display: block; width: 100%; height: 100%; object-fit: cover; }
.article-kicker { margin-bottom: 20px; font: 11px/1.2 basel, Arial, sans-serif; letter-spacing: .08em; }
.author-row { display: flex; align-items: center; gap: 12px; margin-bottom: 40px; font-size: 13px; }
.author-row img { width: 40px; height: 40px; border-radius: 50%; object-fit: cover; }
.author-row > div { display: grid; gap: 3px; }
.author-meta { color: var(--muted); font-size: 11px; }
.author-meta b { padding: 0 4px; font-weight: 400; }
h1, h2, h3 { font-weight: 300; }
.research-article h1 { margin: 0 0 18px; font: 300 68px/1 martina, Georgia, serif; }
.research-article .dek { margin: 0 0 24px; font-size: 28px; line-height: 1.14; }
.source-line { color: var(--muted); font-size: 13px !important; }
.research-article p { margin: 20px 0; font-size: 18px; line-height: 1.35; }
.research-article p a { text-decoration: underline; }
.embed-shell { width: 100%; margin: 42px 0; padding: 28px 40px; overflow: hidden; border-radius: 12px; background: #fff; }
.report-embed { display: block; width: 100%; border: 0; background: transparent; }
.embed-leaderboard { height: 690px; }
.embed-task, .embed-length { height: 440px; }
.embed-failure { height: 580px; }
.embed-example { height: 640px; }
.embed-generation { height: 500px; }
.article-section { margin-top: 76px; scroll-margin-top: 112px; }
.research-article h2 { margin: 0 0 24px; font: 300 48px/1.08 martina, Georgia, serif; }
.research-article h3 { margin: 48px 0 10px; font: 300 34px/1.16 martina, Georgia, serif; }
.takeaways { display: grid; gap: 14px; padding-left: 22px; }
.takeaways li { padding-left: 3px; font-size: 18px; line-height: 1.5; }
.takeaways li::marker { font-size: 14px; }
.takeaways strong { font-weight: 500; }
.signal-table-wrap { width: 100%; overflow-x: auto; }
.signal-table { width: 100%; border-collapse: collapse; font-size: 14px; line-height: 1.45; }
.signal-table th, .signal-table td { padding: 16px 14px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
.signal-table thead th { color: var(--muted); font-size: 12px; font-weight: 400; }
.signal-table tbody th { width: 23%; font-weight: 500; }
.signal-table tbody td { width: 38.5%; }
.signal-table tbody th span { display: block; margin-top: 4px; color: var(--muted); font: 12px basel, Arial, sans-serif; }
.inline-formula { font: 20px/1.4 Georgia, serif; white-space: nowrap; }
.references ol { display: grid; gap: 12px; padding-left: 22px; font-size: 14px; }
.references li { padding-left: 4px; }
.article-footer { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 64px; padding-top: 24px; border-top: 1px solid var(--line); }
.article-footer a { display: inline-flex; justify-content: space-between; gap: 20px; align-items: center; min-height: 48px; padding: 0 16px; border: 1px solid var(--ink); border-radius: 0; font-size: 13px; text-decoration: none; }
.official-link { background: var(--ink); color: var(--paper); }
.research-layout { position: relative; }
.article-rail { position: absolute; top: 0; right: 0; height: 100%; display: flex; align-items: flex-end; justify-content: flex-end; width: calc(var(--rail-width) + 55px); }
.rail-controls { position: sticky; bottom: 31px; width: max-content; max-width: 100%; }
.toc { display: flex; flex-direction: column; align-items: flex-end; }
.toc a, .back-link { position: relative; display: flex; align-items: center; justify-content: flex-end; gap: 8px; width: max-content; max-width: 100%; height: 20px; padding: 0; color: var(--muted); font: 14px/1.2 basel, Arial, sans-serif; text-decoration: none; }
.rail-label { display: block; max-width: 200px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; transform: translateY(-.4px); }
.rail-line { position: relative; flex-shrink: 0; width: 64px; height: 1px; transition: width .25s ease-out; }
.rail-line::before { content: ""; position: absolute; left: 0; top: 0; width: 100%; height: 1px; background: currentColor; }
.rail-line::after { content: ""; position: absolute; right: 0; top: 0; width: 10px; height: 10px; border: 1px solid currentColor; transform: translateY(-50%) scale(0); transition: transform .25s ease-out; }
.toc a[aria-current="location"] .rail-line::before, .rail-return::before { width: calc(100% - 18px); }
.toc a[aria-current="location"] .rail-line::after { transform: translateY(-50%) scale(1); }
.toc a:hover .rail-line, .toc a:focus-visible .rail-line, .back-link:hover .rail-line, .back-link:focus-visible .rail-line { width: 96px; }
.toc a:focus-visible, .back-link:focus-visible { outline: 1px solid var(--ink); outline-offset: 4px; }
/* Center the return link between the 56px site header and the first TOC line. */
.back-link { position: absolute; right: 0; top: calc((56px + 141px - 100vh) / 2); }
.rail-return svg { position: absolute; right: 0; top: -5px; width: 10px; height: 10px; fill: none; stroke: currentColor; stroke-width: .7px; }
.rail-return::after { content: none; }
.article-top-anchor { position: absolute; top: 0; left: 0; }
@media (max-width: 980px) {
  .research-header, .research-layout { width: min(845px, calc(100% - 48px)); }
  .research-layout { grid-template-columns: minmax(0, 1fr); margin-top: 64px; }
  .article-rail { position: static; grid-row: 1; padding: 0; height: auto; width: auto; max-width: 100%; }
  .rail-controls { position: static; }
  .back-link { position: static; }
  .toc { display: none; }
  .article-rail { gap: 0; }
  .cover { margin-bottom: 36px; }
}
@media (max-width: 620px) {
  .research-header { width: calc(100% - 32px); height: 56px; margin-top: 12px; }
  .research-layout { width: calc(100% - 32px); margin-top: 30px; }
  .research-article h1 { font-size: 44px; }
  .research-article .dek { font-size: 22px; }
  .research-article p, .takeaways li { font-size: 16px; }
  .research-article h2 { font-size: 38px; }
  .research-article h3 { font-size: 28px; }
  .author-meta { display: block; max-width: 250px; }
  .embed-shell { padding: 20px 16px; }
  .embed-leaderboard { height: 620px; }
  .embed-task, .embed-length { height: 380px; }
  .embed-failure { height: 480px; }
  .embed-example { height: 560px; }
  .embed-generation { height: 430px; }
  .signal-table { min-width: 550px; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } .rail-line, .rail-line::after { transition: none; } }

/* Shared navigation uses the research paper palette without changing leaderboard styles. */
.research-page .site-header {
  --bg: var(--paper); --bg2: var(--wash); --bg3: #e8e4de;
  --border: var(--line); --text: var(--ink); --text2: var(--muted); --text3: var(--muted); --accent: var(--ink);
  color: var(--text); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}
.site-header .nav-home-btn { color: var(--text); }
.site-header .nav-app-btn { color: var(--ink); background: transparent; border-color: var(--line); }
.site-header .nav-app-btn:hover { background: var(--wash); border-color: var(--ink); }
.site-header .mega-card[data-active="true"] { background: var(--wash); border-color: var(--line); }
.site-header .mega-menu, .site-header .lang-menu { box-shadow: 0 8px 24px rgba(26,25,25,.08); }
.site-header .nav-lang-dd:focus-within .lang-menu,
.site-header .nav-lang-dd[data-open="true"] .lang-menu { display: flex; }
.site-header .nav-lang-dd[data-open="false"] .lang-menu { display: none; }
.lang-en { display: none !important; }
html[data-lang="en"] .lang-en { display: revert !important; }
html[data-lang="en"] .lang-zh { display: none !important; }
.research-layout { margin-top: 110px; }
.signal-table tbody th .lang-zh, .signal-table tbody th .lang-en { margin: 0; color: inherit; font: inherit; }
html[data-lang="zh"] .research-article h1,
html[data-lang="zh"] .research-article h2,
html[data-lang="zh"] .research-article h3 { font-family: martina, "Songti SC", "Noto Serif CJK SC", Georgia, serif; }
html[data-lang="zh"] .research-article p { line-height: 1.65; }
html[data-lang="zh"] .research-article .dek { line-height: 1.35; }
.research-provenance { margin-top: 64px; padding-top: 24px; border-top: 1px solid var(--line); }
.research-provenance h3 { margin-top: 0; font-size: 28px; }
.research-provenance p, .research-provenance a { font-size: 13px; color: var(--muted); }
.skip-link { z-index: 400; }
@media (max-width: 1100px) {
  .research-page .nav-container { gap: 0; }
  .research-page .nav-container > a, .research-page .nav-dropdown > a, .research-page .nav-dropdown > button { padding: 8px 10px; }
}