:root {
  --paper: #f5f3ef;
  --paper-2: #fffefb;
  --ink: #1b1d1f;
  --muted: #6b6e72;
  --line: #ddd9d2;
  --dark: #121a26;
  --blue: #2f6fd0;
  --blue-soft: #e8f0fc;
  --red: #c8372f;
  --red-soft: #fbeceb;
  --display: 'Space Grotesk', 'Helvetica Neue', Arial, sans-serif;
  --body: 'Inter', 'Helvetica Neue', Arial, sans-serif;
  --wrap: 1120px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 88px; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--body);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; }
img, video { max-width: 100%; display: block; }
.wrap { width: 100%; max-width: var(--wrap); margin: 0 auto; padding: 0 28px; }

/* ---------- top bar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 20;
  background: rgba(245, 243, 239, .88);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.topbar__inner { display: flex; align-items: center; gap: 28px; height: 64px; }
.topbar__mark { font-family: var(--display); font-weight: 700; letter-spacing: -.02em; font-size: 19px; }
.topbar__mark span { color: var(--blue); }
.topbar nav { margin-left: auto; display: flex; gap: 24px; font-size: 14.5px; color: var(--muted); }
.topbar nav a:hover { color: var(--ink); }
@media (max-width: 720px) { .topbar nav { display: none; } }

/* ---------- hero ---------- */
.hero { padding: 88px 0 64px; border-bottom: 1px solid var(--line); }
.eyebrow {
  font-family: var(--display); font-size: 13px; font-weight: 600;
  letter-spacing: .18em; text-transform: uppercase; color: var(--blue);
}
.hero h1 {
  font-family: var(--display); font-weight: 700; letter-spacing: -.035em;
  font-size: clamp(64px, 11vw, 132px); line-height: .92; margin: 18px 0 0;
}
.hero h1 .dot { color: var(--blue); }
.hero__sub {
  font-family: var(--display); font-weight: 500; letter-spacing: -.01em;
  font-size: clamp(21px, 2.6vw, 30px); line-height: 1.3; margin: 22px 0 0; max-width: 860px;
}
.hero__authors { margin: 30px 0 0; font-size: 17px; }
.hero__authors b { font-weight: 600; }
.hero__affil { margin: 6px 0 0; color: var(--muted); font-size: 15px; }
.hero__note { margin: 4px 0 0; color: var(--muted); font-size: 13.5px; }

.links { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 32px; }
.btn {
  display: inline-flex; align-items: center; gap: 9px;
  padding: 11px 20px; border-radius: 999px;
  border: 1px solid var(--line); background: var(--paper-2);
  font-size: 14.5px; font-weight: 600; text-decoration: none;
  transition: border-color .15s, background .15s, transform .15s;
}
.btn:hover { border-color: var(--ink); transform: translateY(-1px); }
.btn--primary { background: var(--dark); border-color: var(--dark); color: #fff; }
.btn--primary:hover { background: #1d2a3d; }
.btn code { font-family: ui-monospace, Menlo, monospace; font-size: 13px; font-weight: 500; }

/* ---------- sections ---------- */
section { padding: 76px 0; border-bottom: 1px solid var(--line); }
.sec-label {
  font-family: var(--display); font-size: 12.5px; font-weight: 600;
  letter-spacing: .18em; text-transform: uppercase; color: var(--muted);
}
h2 {
  font-family: var(--display); font-weight: 700; letter-spacing: -.025em;
  font-size: clamp(32px, 4.4vw, 46px); line-height: 1.12; margin: 14px 0 0;
}
.lead { font-size: 19px; line-height: 1.6; margin: 22px 0 0; max-width: 760px; color: #33363a; }
p { margin: 18px 0 0; }
.muted { color: var(--muted); }

/* ---------- problem figure ---------- */
.figure {
  margin-top: 40px; background: var(--paper-2);
  border: 1px solid var(--line); border-radius: 16px; padding: 32px 28px 24px;
}
.figure svg { width: 100%; height: auto; }
.figure figcaption { margin-top: 18px; font-size: 14.5px; color: var(--muted); }

/* ---------- idea cards ---------- */
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; margin-top: 42px; }
@media (max-width: 860px) { .cards { grid-template-columns: 1fr; } }
.card {
  background: var(--paper-2); border: 1px solid var(--line);
  border-radius: 16px; padding: 30px 28px;
}
.card__num {
  font-family: var(--display); font-size: 13px; font-weight: 700;
  letter-spacing: .14em; color: var(--blue);
}
.card h3 {
  font-family: var(--display); font-size: 21px; font-weight: 600;
  letter-spacing: -.01em; margin: 12px 0 0; line-height: 1.3;
}
.card p { font-size: 15.5px; line-height: 1.6; color: #43474b; }

.callout {
  margin-top: 34px; padding: 26px 30px; border-radius: 16px;
  background: var(--blue-soft); border: 1px solid #cfe0f8;
}
.callout p { margin: 0; font-size: 16.5px; }
.callout b { font-weight: 600; }

/* ---------- video ---------- */
.video-shell {
  margin-top: 40px; border: 1px solid var(--line); border-radius: 16px;
  overflow: hidden; background: #000;
}
.video-shell video { width: 100%; height: auto; }
.chapters { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 18px; }
.chip {
  font-size: 14px; font-weight: 600; padding: 8px 16px; border-radius: 999px;
  border: 1px solid var(--line); background: var(--paper-2); cursor: pointer;
  font-family: var(--body); color: var(--ink);
}
.chip:hover { border-color: var(--ink); }
.chip--red { background: var(--red-soft); border-color: #f0cfcc; color: var(--red); }
.chip--blue { background: var(--blue-soft); border-color: #cfe0f8; color: var(--blue); }

/* ---------- benchmark ---------- */
.bench { display: grid; grid-template-columns: 1.25fr 1fr; gap: 36px; margin-top: 42px; align-items: start; }
@media (max-width: 900px) { .bench { grid-template-columns: 1fr; } }
.bench img { border: 1px solid var(--line); border-radius: 14px; background: #fff; }
table { width: 100%; border-collapse: collapse; font-size: 15px; }
th, td { text-align: left; padding: 13px 10px; border-bottom: 1px solid var(--line); }
th { font-family: var(--display); font-size: 12.5px; font-weight: 600; letter-spacing: .07em; text-transform: uppercase; color: var(--muted); }
td.num { text-align: right; font-variant-numeric: tabular-nums; }
tr.is-ref td { font-weight: 600; }

/* ---------- citation ---------- */
.bib {
  margin-top: 28px; position: relative;
  background: var(--dark); border-radius: 16px; padding: 28px 30px;
  overflow-x: auto;
}
.bib pre {
  margin: 0; font-family: ui-monospace, Menlo, monospace;
  font-size: 13.5px; line-height: 1.7; color: #dfe6f0; white-space: pre;
}
.copy {
  position: absolute; top: 18px; right: 18px;
  font-family: var(--body); font-size: 12.5px; font-weight: 600;
  padding: 7px 14px; border-radius: 999px; cursor: pointer;
  background: rgba(255,255,255,.1); color: #dfe6f0; border: 1px solid rgba(255,255,255,.2);
}
.copy:hover { background: rgba(255,255,255,.18); }

/* ---------- footer ---------- */
footer { padding: 46px 0 64px; }
.footer__inner { display: flex; align-items: center; gap: 22px; flex-wrap: wrap; }
.footer__inner img { height: 24px; width: auto; opacity: .75; }
.footer__inner p { margin: 0; font-size: 14px; color: var(--muted); }
.footer__inner a { color: var(--muted); }
.footer__inner a:hover { color: var(--ink); }

/* ---------- split clips ---------- */
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin-top: 34px; }
@media (max-width: 820px) { .grid2 { grid-template-columns: 1fr; } }
.clip { margin: 0; }
.clip video {
  width: 100%; border-radius: 14px; border: 1px solid var(--line);
  background: #000; display: block;
}
.clip figcaption { margin-top: 12px; font-size: 14.5px; line-height: 1.55; color: #43474b; }
.tag {
  display: inline-block; font-size: 12px; font-weight: 600; letter-spacing: .04em;
  padding: 3px 10px; border-radius: 999px; margin-right: 8px; vertical-align: 1px;
}
.tag--red { background: var(--red-soft); color: var(--red); }
.tag--blue { background: var(--blue-soft); color: var(--blue); }
h3.sub {
  font-family: var(--display); font-size: 22px; font-weight: 600;
  letter-spacing: -.01em; margin: 46px 0 0;
}

/* ---------- interactive demo ---------- */
.demo {
  margin-top: 34px; background: var(--paper-2);
  border: 1px solid var(--line); border-radius: 16px; padding: 22px 24px 24px;
}
.demo svg { width: 100%; height: auto; display: block; }
.demo--sweep { margin-top: 22px; }
#demo-sweep { cursor: ew-resize; touch-action: none; }
.legend { display: flex; flex-wrap: wrap; gap: 18px; margin-top: 10px; font-size: 13.5px; color: #43474b; }
.legend i { display: inline-block; width: 18px; height: 3px; border-radius: 2px; margin-right: 7px; vertical-align: 3px; }
.sw--ref { background: #c9c5bd; }
.sw--red { background: var(--red); }
.sw--blue { background: var(--blue); }

.sliders {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px 26px;
  margin-top: 22px; padding-top: 20px; border-top: 1px solid var(--line);
  align-items: end;
}
@media (max-width: 820px) { .sliders { grid-template-columns: 1fr 1fr; } }
.sliders label { font-size: 13.5px; color: var(--muted); display: block; }
.sliders label b { color: var(--ink); font-variant-numeric: tabular-nums; }
.sliders input[type=range] { width: 100%; accent-color: var(--blue); margin-top: 6px; }
.sliders .chip { align-self: center; }

.readout { margin-top: 20px; padding-top: 18px; border-top: 1px solid var(--line); display: grid; gap: 10px; }
.stat { display: flex; align-items: baseline; gap: 12px; flex-wrap: wrap; font-size: 15px; }
.stat .k { width: 240px; color: var(--muted); }
.stat .v { font-family: ui-monospace, Menlo, monospace; font-size: 17px; font-weight: 600; font-variant-numeric: tabular-nums; }
.stat .v--red { color: var(--red); }
.stat .v--blue { color: var(--blue); }
.stat .arrow { color: var(--muted); }
.stat .d { font-size: 13.5px; color: var(--muted); }
@media (max-width: 620px) { .stat .k { width: 100%; } }

/* demo: dark plot panel, chunk colours, zone swatches */
.sw--chunks { background: linear-gradient(90deg,#ffb454 0 33%,#4fd1c5 33% 66%,#c79bff 66% 100%); }
.sw--white { background: #1b1d1f; box-shadow: inset 0 0 0 1px #1b1d1f; }
.sw--eps { background: #b9b5ac; }
.sw--delay { background: #8ab4ff; }
.sw--blendz { background: #ffb454; }
.warn {
  margin-top: 14px; font-size: 13.5px; line-height: 1.5; color: var(--muted);
  padding: 10px 14px; background: var(--red-soft); border-radius: 10px; display: none;
}
.demo__foot { margin-top: 16px; }
.sliders label i { font-style: italic; }