/* =========================================================
   Collapsed Effective Operators — project page
   Palette derived from the paper's own figures:
   ink #111827 · slate #4b5563 · amber #f59e0b · violet #8b5cf6 · red #dc2626
   ========================================================= */

:root {
  --ink:        #14161c;
  --ink-soft:   #3a3f4b;
  --slate:      #5b6472;
  --muted:      #8a909c;
  --line:       #e7e6e2;
  --line-soft:  #efeee9;
  --paper:      #ffffff;
  --paper-2:    #faf9f6;
  --tint:       #f6f5f1;

  --violet:     #6d28d9;
  --violet-2:   #8b5cf6;
  --amber:      #d98a12;
  --amber-soft: #f59e0b;
  --red:        #dc2626;

  --spectral: linear-gradient(90deg, #2563eb 0%, #06b6d4 32%, #f59e0b 66%, #ef4444 100%);

  --maxw: 1080px;
  --maxw-narrow: 720px;

  --serif: "Newsreader", Georgia, "Times New Roman", serif;
  --sans:  "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --mono:  "JetBrains Mono", ui-monospace, "SF Mono", Menlo, monospace;

  --shadow-sm: 0 1px 2px rgba(20,22,28,.05), 0 2px 8px rgba(20,22,28,.04);
  --shadow-md: 0 6px 24px rgba(20,22,28,.08), 0 1px 3px rgba(20,22,28,.05);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 84px; }

body {
  margin: 0;
  font-family: var(--sans);
  color: var(--ink);
  background: var(--paper);
  font-size: 17px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: var(--violet); text-decoration: none; transition: color .15s ease; }
a:hover { color: var(--red); }

p { margin: 0 0 1.1em; color: var(--ink-soft); }
em { font-style: italic; }
strong { font-weight: 600; color: var(--ink); }
sup { font-size: .62em; font-weight: 600; }

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 28px; }
.wrap--narrow { max-width: var(--maxw-narrow); }

/* =================== NAV =================== */
.nav {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,.82);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--line-soft);
}
.nav__inner {
  max-width: var(--maxw); margin: 0 auto; padding: 0 28px;
  height: 60px; display: flex; align-items: center; justify-content: space-between;
}
.nav__brand {
  display: flex; align-items: center; gap: 10px;
  font-weight: 600; font-size: 15px; color: var(--ink); letter-spacing: -.01em;
}
.nav__brand:hover { color: var(--ink); }
.nav__mark {
  width: 18px; height: 18px; border-radius: 5px;
  background: var(--spectral);
  box-shadow: inset 0 0 0 2px rgba(255,255,255,.6);
}
.nav__links { display: flex; gap: 26px; }
.nav__links a {
  color: var(--slate); font-size: 14px; font-weight: 500;
  position: relative; padding: 4px 0;
}
.nav__links a:hover { color: var(--ink); }
.nav__links a::after {
  content: ""; position: absolute; left: 0; right: 100%; bottom: -1px; height: 2px;
  background: var(--ink); transition: right .2s ease;
}
.nav__links a:hover::after { right: 0; }

/* =================== HERO =================== */
.hero {
  text-align: center;
  padding: 72px 0 0;
  position: relative;
  background:
    radial-gradient(1200px 380px at 50% -120px, rgba(139,92,246,.07), transparent 70%),
    var(--paper);
}

.venue {
  display: inline-flex; align-items: center; gap: 12px;
  margin-bottom: 26px;
}
.venue__pill {
  font-weight: 700; font-size: 12.5px; letter-spacing: .08em; text-transform: uppercase;
  color: #fff; padding: 5px 12px; border-radius: 999px;
  background: var(--ink);
}
.venue__sep { color: var(--muted); font-size: 13px; letter-spacing: .02em; }

.title {
  font-family: var(--serif);
  font-weight: 500;
  font-size: clamp(2.1rem, 5.2vw, 3.7rem);
  line-height: 1.08;
  letter-spacing: -.02em;
  margin: 0 auto 28px;
  max-width: none;
  color: var(--ink);
}
.title__sub { font-style: italic; font-weight: 400; color: var(--ink-soft); }

/* author photo row */
.authors {
  list-style: none; margin: 0 0 22px; padding: 0;
  display: flex; flex-wrap: wrap; justify-content: center; gap: 8px 26px;
}
.author { display: flex; flex-direction: column; align-items: center; width: 132px; }
.author > a { display: flex; flex-direction: column; align-items: center; gap: 9px; color: var(--ink); }
.author__img {
  width: 76px; height: 76px; border-radius: 50%; object-fit: cover;
  background: var(--tint);
  box-shadow: 0 0 0 1px var(--line), var(--shadow-sm);
  transition: transform .2s ease, box-shadow .2s ease;
}
.author > a:hover .author__img {
  transform: translateY(-3px);
  box-shadow: 0 0 0 2px var(--violet-2), 0 8px 20px rgba(109,40,217,.18);
}
.author__name { font-weight: 600; font-size: 14.5px; letter-spacing: -.01em; line-height: 1.2; }
.author__name .mark { color: var(--amber); font-weight: 700; margin-left: 1px; }
.author > a:hover .author__name { color: var(--violet); }
.author > a:hover .author__name .mark { color: var(--amber); }
.author__aff { font-size: 11.5px; color: var(--muted); margin-top: 3px; line-height: 1.3; }

.affils {
  max-width: 760px; margin: 0 auto 10px; padding: 0 10px;
  color: var(--slate); font-size: 13.5px; line-height: 1.6;
}
.contrib { color: var(--muted); font-size: 13px; margin: 0 0 30px; }
.contrib span { color: var(--amber); font-weight: 700; }

/* action buttons */
.actions { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px; padding-bottom: 56px; }
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  font-weight: 600; font-size: 14.5px;
  padding: 11px 20px; border-radius: 999px;
  color: var(--ink); background: var(--paper);
  border: 1px solid var(--line);
  box-shadow: var(--shadow-sm);
  transition: transform .15s ease, box-shadow .15s ease, border-color .15s ease, color .15s ease;
}
.btn:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); color: var(--ink); border-color: #d9d8d2; }
.btn--primary { background: var(--ink); color: #fff; border-color: var(--ink); }
.btn--primary:hover { color: #fff; background: #20232c; }
.btn--soon { color: var(--muted); cursor: default; border-style: dashed; box-shadow: none; }
.btn--soon:hover { transform: none; box-shadow: none; border-color: var(--line); color: var(--muted); }
.btn__ico { font-family: var(--mono); font-size: 13px; opacity: .9; }
.btn__tag {
  font-size: 10.5px; font-weight: 700; letter-spacing: .04em; text-transform: uppercase;
  padding: 2px 7px; border-radius: 999px; margin-left: 2px;
  background: var(--amber-soft); color: #3a2600;
}

/* teaser figure */
.teaser {
  max-width: 1180px; margin: 64px auto 0;
  padding: 56px 28px 0;
  border-top: 1px solid var(--line);
}
.teaser picture, .teaser img { display: block; width: 100%; height: auto; }
.teaser img {
  border-radius: 14px;
  background: var(--paper);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--line-soft);
}
.teaser figcaption {
  max-width: 920px; margin: 20px auto 0;
  font-size: 14px; line-height: 1.65; color: var(--slate); text-align: left;
}
.teaser figcaption strong { color: var(--ink); }
.dot { display: inline-block; width: 9px; height: 9px; border-radius: 50%; vertical-align: middle; margin: 0 1px; }
.dot--red { background: #c0392b; } .dot--blue { background: #2f6fb0; } .dot--grey { background: #9aa0a6; }

/* =================== SECTIONS =================== */
.section { padding: 84px 0; border-top: 1px solid var(--line-soft); }
.section--tint { background: var(--paper-2); }

.h2 {
  font-family: var(--serif); font-weight: 500;
  font-size: clamp(1.7rem, 3.4vw, 2.4rem); letter-spacing: -.02em; line-height: 1.1;
  margin: 0 0 1.1em; color: var(--ink);
  display: flex; align-items: baseline; gap: 16px;
}
.h2__num {
  font-family: var(--mono); font-size: .42em; font-weight: 500;
  color: var(--violet); letter-spacing: .05em;
  border: 1px solid var(--line); border-radius: 6px; padding: 3px 7px;
  position: relative; top: -.35em; background: var(--paper);
}
.h3 { font-family: var(--serif); font-weight: 500; font-size: 1.45rem; letter-spacing: -.01em; margin: 0 0 .55em; color: var(--ink); }

.lede {
  font-family: var(--serif); font-size: 1.32rem; line-height: 1.5; font-weight: 380;
  color: var(--ink); margin-bottom: 1em;
}

/* equations */
.eq {
  position: relative;
  margin: 1.4em 0; padding: 18px 22px 18px 26px;
  background: var(--paper); border: 1px solid var(--line);
  border-radius: 10px; box-shadow: var(--shadow-sm);
  overflow-x: auto;
}
.eq::before {
  content: ""; position: absolute; left: 0; top: 0; bottom: 0; width: 4px;
  background: var(--spectral); border-radius: 10px 0 0 10px;
}

/* =================== IDEA =================== */
.idea { display: grid; grid-template-columns: 1.25fr .9fr; gap: 48px; align-items: center; margin-bottom: 56px; }
.idea__fig { margin: 0; }
.idea__fig img {
  width: 100%; height: auto; padding: 26px;
  background: var(--paper); border: 1px solid var(--line); border-radius: 14px;
  box-shadow: var(--shadow-md);
}
.idea__fig figcaption, .split__fig figcaption {
  font-size: 13px; color: var(--muted); margin-top: 12px; line-height: 1.55; text-align: center;
}

.cards { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; }
.card {
  background: var(--paper); border: 1px solid var(--line); border-radius: 14px;
  padding: 22px 20px; box-shadow: var(--shadow-sm);
  transition: transform .18s ease, box-shadow .18s ease;
}
.card:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); }
.card__k {
  display: block; font-weight: 600; font-size: 15px; color: var(--ink); margin-bottom: 8px;
  padding-bottom: 8px; border-bottom: 1px solid var(--line-soft);
}
.card p { font-size: 14px; line-height: 1.6; margin: 0; color: var(--slate); }

/* =================== SPLIT (background / method) =================== */
.split { display: grid; grid-template-columns: 1.05fr .95fr; gap: 52px; align-items: center; }
.split--rev .split__text { order: 2; }
.split__fig { margin: 0; }
.split__fig img {
  width: 100%; height: auto; padding: 22px;
  background: var(--paper); border: 1px solid var(--line); border-radius: 14px; box-shadow: var(--shadow-md);
}

/* =================== RESULTS =================== */
.result {
  display: grid; grid-template-columns: 1.15fr .85fr; gap: 48px; align-items: center;
  padding: 36px 0; border-top: 1px solid var(--line-soft);
}
.result--rev .result__media { order: 2; }
.result__media img, .result__media picture { display: block; width: 100%; height: auto; border-radius: 12px; }
.result__media img {
  background: var(--paper); border: 1px solid var(--line-soft); box-shadow: var(--shadow-sm);
}
.result__media--pad img { padding: 16px 18px; }
.result__text--full { grid-column: 1 / -1; }
.result:has(.result__text--full) { grid-template-columns: 1fr; }

/* =================== TABLES =================== */
.tbl { width: 100%; border-collapse: collapse; font-size: 14.5px; margin: 16px 0 6px; }
.tbl th, .tbl td { padding: 9px 14px; text-align: right; border-bottom: 1px solid var(--line-soft); }
.tbl th:first-child, .tbl td:first-child { text-align: left; }
.tbl thead th { font-weight: 600; color: var(--slate); font-size: 13px; border-bottom: 1.5px solid var(--line); }
.tbl tbody td { font-variant-numeric: tabular-nums; color: var(--ink-soft); }
.tbl .win { color: var(--violet); font-weight: 700; }
.tbl__rule td { border-top: 1px solid var(--line); }
.tbl--wide { max-width: 560px; }
.tbl-scroll { overflow-x: auto; }
.cap { font-size: 12.5px; color: var(--muted); margin: 4px 0 0; }

/* =================== BIBTEX =================== */
.bib { position: relative; }
.bib pre {
  margin: 0; padding: 24px 22px; overflow-x: auto;
  background: #15171e; border-radius: 14px; box-shadow: var(--shadow-md);
}
.bib code {
  font-family: var(--mono); font-size: 13px; line-height: 1.7; color: #d7dae2;
  white-space: pre;
}
.bib__copy {
  position: absolute; top: 14px; right: 14px;
  font-family: var(--sans); font-size: 12.5px; font-weight: 600;
  color: #cdd2dc; background: rgba(255,255,255,.08); border: 1px solid rgba(255,255,255,.14);
  padding: 6px 14px; border-radius: 8px; cursor: pointer; transition: all .15s ease;
}
.bib__copy:hover { background: rgba(255,255,255,.16); color: #fff; }
.bib__copy.is-done { background: var(--amber-soft); color: #3a2600; border-color: transparent; }

/* =================== FOOTER =================== */
.footer { padding: 54px 0 60px; border-top: 1px solid var(--line); text-align: center; background: var(--paper-2); }
.footer__links { display: flex; justify-content: center; gap: 28px; margin-bottom: 18px; }
.footer__links a { font-weight: 600; font-size: 14.5px; color: var(--ink); }
.footer__links a:hover { color: var(--violet); }
.footer__note { font-size: 12.5px; color: var(--muted); line-height: 1.7; margin: 0; }

/* =================== RESPONSIVE =================== */
@media (max-width: 900px) {
  .idea, .split, .result { grid-template-columns: 1fr; gap: 30px; }
  .split--rev .split__text, .result--rev .result__media { order: 0; }
  .cards { grid-template-columns: repeat(2, 1fr); }
  .idea__fig, .split__fig { max-width: 460px; margin: 0 auto; }
}
@media (max-width: 640px) {
  body { font-size: 16px; }
  .nav__links { display: none; }
  .section { padding: 56px 0; }
  .cards { grid-template-columns: 1fr; }
  .author { width: 116px; }
  .author__img { width: 64px; height: 64px; }
  .teaser { padding-left: 16px; padding-right: 16px; }
  .h2 { gap: 12px; }
  .venue__sep { display: none; }
  .venue { gap: 0; }
}