/* Super Library Agent — project page.
   No external requests: system fonts, no CDN, no analytics. */

:root {
  --bg: #fbfbf9;
  --surface: #ffffff;
  --surface-2: #f4f4f1;
  --ink: #17181a;
  --ink-2: #4a4d52;
  --ink-3: #7c8087;
  --line: #e2e2dd;
  --accent: #1f6f68;
  --accent-soft: #e6f0ee;
  --add: #1f7a3f;
  --add-bg: #e7f5ec;
  --del: #a5321f;
  --del-bg: #fbeae7;
  --radius: 10px;
  --page: min(92vw, 1120px);
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
    "Liberation Mono", monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue",
    Arial, "Noto Sans KR", sans-serif;
  --display: "Avenir Next", Avenir, "Segoe UI Variable", "Segoe UI", Helvetica, Arial, sans-serif;
}


* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 4.5rem; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

p { max-width: none; }
/* long measures need more leading */
main p, main li { line-height: 1.7; }
a { color: var(--accent); }
a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 4px;
}

/* ---------- nav ---------- */

.nav {
  position: sticky;
  top: 0;
  z-index: 20;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(1.4) blur(8px);
  border-bottom: 1px solid var(--line);
}
.nav-inner {
  max-width: var(--page);
  margin: 0 auto;
  padding: 0.6rem 1.5rem;
  display: flex;
  align-items: center;
  gap: 1.5rem;
}
.nav-mark { font-weight: 700; letter-spacing: -0.01em; }
.nav-links {
  display: flex;
  gap: 1.1rem;
  margin-left: auto;
  font-size: 0.9rem;
  overflow-x: auto;
}
.nav-links a {
  color: var(--ink-2);
  text-decoration: none;
  white-space: nowrap;
  padding-bottom: 2px;
  border-bottom: 2px solid transparent;
}
.nav-links a:hover { color: var(--ink); }
.nav-links a.active { color: var(--ink); border-bottom-color: var(--accent); }

/* ---------- layout ---------- */

.wrap { max-width: var(--page); margin: 0 auto; padding: 0 1.5rem; }

section { padding: 3.5rem 0; border-top: 1px solid var(--line); }
section:first-of-type { border-top: 0; }

h1, h2, h3 { line-height: 1.25; letter-spacing: -0.015em; }
h2 { font-size: clamp(1.3rem, 2.05vw, 1.9rem); margin: 0 0 0.5rem; }
h3 {
  font-size: 1.15rem;
  font-weight: 650;
  color: var(--ink-2);
  margin: 2rem 0 0.5rem;
}
/* h4 groups content inside an h3 section, so it must read a step down from it */
h4 { font-size: 1.02rem; font-weight: 650; line-height: 1.3; margin: 1.7rem 0 0.6rem; }

.kicker {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 1rem;
  padding-bottom: 0.35rem;
  border-bottom: 2px solid var(--accent);
}
.lede { color: var(--ink-2); margin-top: 0; }

/* ---------- hero ---------- */

.hero { padding: 4.2rem 0 3.2rem; text-align: center; }
.hero h1 {
  font-size: clamp(1.5rem, 2.55vw, 2rem);
  font-weight: 700;
  color: var(--ink);
  margin: 0.7rem auto 1.2rem;
  max-width: 54ch;
  text-wrap: balance;
}
.hero-message {
  --hero-copy-width: 64rem;
  margin: 2.8rem auto 0;
  padding-top: 2.5rem;
  border-top: 1px solid var(--line);
}
.hero-hook {
  width: min(100%, var(--hero-copy-width));
  margin: 0 auto;
  color: var(--accent);
  font-size: clamp(1.5rem, 2.55vw, 2rem);
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: -0.015em;
  text-align: center;
  white-space: nowrap;
}
.hero-overview {
  width: min(100%, var(--hero-copy-width));
  margin: 1.35rem auto 0;
  color: var(--ink-2);
  font-size: clamp(1.02rem, 1.6vw, 1.2rem);
  line-height: 1.65;
  text-align: center;
  text-wrap: balance;
}
.hero-proof {
  display: grid;
  grid-template-columns: minmax(14rem, 0.58fr) minmax(0, 1.42fr);
  align-items: center;
  gap: 1.8rem;
  margin-top: 2rem;
  padding-top: 2rem;
  border-top: 1px solid var(--line);
  text-align: left;
}
.hero-stats {
  margin: 0;
  padding-right: 1.35rem;
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.7rem;
  border-right: 1px solid var(--line);
}
.hero-stats > div {
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  min-height: 4.6rem;
  padding: 0.9rem 1rem 0.85rem 1.1rem;
  border: 1px solid color-mix(in srgb, var(--accent) 18%, var(--line));
  border-radius: var(--radius);
  background:
    linear-gradient(115deg, var(--surface) 52%, color-mix(in srgb, var(--accent-soft) 72%, var(--surface)) 100%);
  box-shadow: 0 12px 28px -25px color-mix(in srgb, var(--accent) 65%, transparent);
}
.hero-stats > div::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 3px;
  background: var(--accent);
}
.hero-stats strong {
  color: var(--accent);
  font-size: clamp(1.65rem, 2.5vw, 2.15rem);
  font-variant-numeric: tabular-nums;
  line-height: 1.1;
  letter-spacing: -0.035em;
  text-align: right;
  white-space: nowrap;
}
.hero-stats span {
  display: grid;
  gap: 0.18rem;
  color: var(--ink);
  font-size: 0.9rem;
  font-weight: 620;
  line-height: 1.25;
}
.hero-stats small {
  color: var(--ink-3);
  font-size: 0.64rem;
  font-weight: 720;
  letter-spacing: 0.11em;
  text-transform: uppercase;
}
.hero-stats strong em {
  display: block;
  color: var(--ink-3);
  font-size: 0.43em;
  font-style: normal;
  font-weight: 650;
  letter-spacing: 0.02em;
}
.hero-animation { min-width: 0; }
.hero-animation-title {
  margin: 0 0 0.35rem;
  color: var(--ink);
  font-size: 1.08rem;
  font-weight: 700;
  text-align: center;
}
.badge {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 650;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 999px;
  padding: 0.28rem 0.85rem;
}
.authors {
  margin: 0 auto 0.35rem;
  max-width: 72ch;
  font-size: 1rem;
  color: var(--ink);
}
.authors sup { color: var(--ink-3); }
.affil { margin: 0 auto; color: var(--ink-2); font-size: 0.94rem; }
.affil-note { color: var(--ink-3); font-size: 0.84rem; margin-top: 0.35rem; }


.buttons {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.6rem;
  margin: 1.7rem 0 0;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.55rem 1.1rem;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink);
  text-decoration: none;
  font-size: 0.92rem;
  font-weight: 550;
  cursor: pointer;
}
.btn:hover { border-color: var(--accent); color: var(--accent); }
.btn-primary {
  background: var(--ink);
  color: var(--bg);
  border-color: var(--ink);
}
.btn-primary:hover { background: var(--accent); border-color: var(--accent); color: #fff; }

/* ---------- narrative sections ---------- */

.section-intro,
.formula-intro,
.method-round > p {
  max-width: 76ch;
  color: var(--ink-2);
  margin: 0.65rem 0 0;
}
.motivation { align-items: center; margin-top: 1.35rem; }
.motivation-copy p { color: var(--ink-2); }
.motivation .fig-flush img {
  width: auto;
  max-width: min(100%, 430px);
  max-height: 270px;
}

.formula-stack {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
  margin-top: 1rem;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}
.formula-block {
  display: grid;
  grid-template-columns: minmax(0, 0.95fr) minmax(16rem, 1.05fr);
  align-items: center;
  gap: 1.4rem;
  padding: 0.75rem 1rem;
  background: transparent;
  border: 0;
  border-radius: 0;
}
.formula-block + .formula-block { border-top: 1px solid var(--line); }
.formula-block.formula-goal {
  background: var(--accent-soft);
}
.formula-expression { min-width: 0; }
.formula-label,
.experiment-number,
.challenge-number {
  display: block;
  color: var(--accent);
  font-size: 0.74rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.equation {
  margin: 0.28rem 0 0;
  overflow-x: auto;
  color: var(--ink);
  font-family: "Latin Modern Math", "STIX Two Math", "Cambria Math", "Computer Modern", serif;
  font-size: clamp(1.08rem, 1.9vw, 1.32rem);
  font-kerning: normal;
  line-height: 1.5;
  white-space: nowrap;
  text-align: left;
}
.equation sub,
.equation sup { font-size: 0.65em; }
.equation var { font-family: inherit; font-style: italic; }
.equation b { font-family: inherit; font-weight: 700; }
.formula-block > p {
  margin: 0;
  color: var(--ink-2);
  font-size: 0.84rem;
  line-height: 1.5;
}
.sum {
  display: inline-grid;
  grid-template-rows: 0.65em 1em 0.65em;
  align-items: center;
  justify-items: center;
  margin-inline: 0.12em;
  vertical-align: middle;
  line-height: 1;
}
.sum > span { font-size: 0.5em; font-family: var(--sans); }
.notation {
  margin-top: 0.7rem;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.notation summary {
  padding: 0.65rem 0;
  color: var(--ink-2);
  font-size: 0.92rem;
  font-weight: 620;
  cursor: pointer;
}
.notation summary:hover { color: var(--accent); }
.notation dl { margin: 0 0 1rem; }
.notation dl > div {
  display: grid;
  grid-template-columns: 6rem 1fr;
  gap: 1rem;
  padding: 0.45rem 0;
}
.notation dt {
  color: var(--ink);
  font-family: "Latin Modern Math", "STIX Two Math", "Cambria Math", "Computer Modern", serif;
  font-size: clamp(1.08rem, 1.9vw, 1.32rem);
  font-kerning: normal;
  line-height: 1.5;
}
.notation dt sub,
.notation dt sup { font-size: 0.65em; }
.notation dt var { font-family: inherit; font-style: italic; }
.notation dt b { font-family: inherit; font-weight: 700; }
.notation dd {
  margin: 0;
  color: var(--ink-2);
  font-size: 0.84rem;
  line-height: 1.5;
}

.method-overview { margin-top: 2rem; }
.method-round { margin-top: 3.25rem; }
.method-round h3 { margin-top: 0; }
.challenge-list { margin-top: 1.35rem; border-top: 1px solid var(--line); }
.challenge-row {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.25fr);
  gap: 1.5rem;
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--line);
}
.challenge-row h4 { margin: 0.35rem 0 0.55rem; }
.challenge-row p { margin: 0; color: var(--ink-2); font-size: 0.94rem; }
.challenge-answer {
  padding: 1rem 1.15rem;
  border-radius: var(--radius);
  background: var(--accent-soft);
}
.challenge-answer h4 { color: var(--accent); margin-top: 0; }

.experiment-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 1.5rem;
}
.experiment-grid article {
  padding: 1.25rem 1.35rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}
.experiment-grid h3 { margin: 0.45rem 0 0.55rem; font-size: 1.08rem; }
.experiment-grid p { margin: 0; color: var(--ink-2); font-size: 0.94rem; }
.experiment-card {
  margin-top: 1.4rem;
  padding: 1rem 1.2rem;
  border: 1px solid var(--line);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius);
  background: var(--surface);
}
.experiment-card p {
  margin: 0.45rem 0 0;
  color: var(--ink-2);
  font-size: 0.94rem;
}
.evaluation-details p { margin: 0 0 1rem; color: var(--ink-2); }

/* ---------- figures ---------- */

figure { margin: 1.8rem 0 0; }
figure img {
  /* cap by height, not width: these are paper figures with very different
     aspect ratios, and letting them fill 1200px makes them dominate the page */
  display: block;
  width: auto;
  max-width: 100%;
  max-height: 380px;
  height: auto;
  margin: 0 auto;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: #fff;
}
/* the method figure is 3.3:1 — width-bound long before it gets tall */
figure.fig-wide img { max-height: none; width: 100%; }
/* the LOC-dynamics panel is a 3-column grid of line charts; it needs the room */
figure.fig-tall img { max-height: 560px; }
/* inside a two-column block the figure should fill its column */
figure.fig-flush { margin-top: 0; }
figure.fig-flush img { max-height: none; width: 100%; }
figcaption {
  margin-top: 0.7rem;
  margin-inline: auto;
  font-size: 0.88rem;
  color: var(--ink-3);
  max-width: min(80ch, 100%);
  text-align: center;
}

/* ---------- notes ---------- */

.stat-note { color: var(--ink-2); font-size: 0.93rem; margin: 0; }

.goal {
  margin-top: 1.8rem;
  padding: 1.3rem 1.5rem;
  border: 1px solid var(--accent);
  border-left-width: 4px;
  border-radius: var(--radius);
  background: var(--accent-soft);
}
.goal-tag {
  font-size: 0.72rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 0.5rem;
  font-weight: 650;
}
.goal-claim {
  font-size: 1.12rem;
  line-height: 1.5;
  color: var(--ink);
  margin: 0;
  max-width: none;
}
/* ---------- pipeline ---------- */

.pipeline {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.7rem;
  margin: 1.6rem 0 0;
  padding: 0;
  counter-reset: none;
}
.pipeline li {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 0.95rem 1rem 0.85rem;
}
.pipeline li + li::before {
  content: "";
  position: absolute;
  left: -0.55rem;
  top: 50%;
  width: 0.4rem;
  height: 1px;
  background: var(--line);
}
.pnum {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.35rem;
  height: 1.35rem;
  border-radius: 999px;
  background: var(--accent);
  color: #fff;
  font-size: 0.78rem;
  font-weight: 700;
  margin-bottom: 0.45rem;
}
.pipeline b { display: block; font-size: 0.95rem; }
.pipeline li > span:not(.pnum) {
  display: block;
  color: var(--ink-2);
  font-size: 0.86rem;
  margin-top: 0.2rem;
  line-height: 1.55;
}

/* ---------- problem -> fix mapping ---------- */

.mapping {
  display: grid;
  grid-template-columns: 5.5rem 1fr 1fr;
  gap: 0.7rem 1.2rem;
  align-items: start;
  margin-top: 1.4rem;
}
.rail {
  margin: 0;
  padding-top: 0.9rem;
  font-size: 0.72rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  font-weight: 650;
  text-align: right;
}
.rail-problem { color: var(--del); }
.rail-fix { color: var(--accent); }
.rail-arrow { padding: 0; }

.track {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  padding: 0.95rem 1.1rem 1rem;
}
.track.fix-track { border-color: var(--accent); background: var(--accent-soft); }

.ptitle {
  margin: 0 0 0.35rem;
  font-weight: 700;
  font-size: 1rem;
  color: var(--del);
}
.pbody { margin: 0; font-size: 0.92rem; color: var(--ink-2); }

.arrow {
  margin: 0;
  text-align: center;
  color: var(--ink-3);
  font-size: 1.1rem;
  line-height: 1;
}

.ftitle {
  margin: 0 0 0.6rem;
  font-weight: 700;
  font-size: 1rem;
  color: var(--accent);
}
.fitems { margin: 0; font-size: 0.9rem; }
.fitems dt { font-weight: 650; color: var(--ink); margin-top: 0.55rem; }
.fitems dt:first-of-type { margin-top: 0; }
.fitems dd { margin: 0.1rem 0 0; color: var(--ink-2); line-height: 1.6; }

/* ---------- pipeline animation ---------- */
/* Animated version of Figure 2(a): one Super Library that grows, rather than
   the paper's two static snapshots L2 and L3. */

.anim { margin: 1.4rem 0 0; }
.anim.anim-compact {
  width: min(100%, 860px);
  margin: 1.5rem auto 0;
}
.anim.anim-hero {
  width: 100%;
  margin: 0 auto;
}
.anim svg {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.anim .cbox { fill: #fff; stroke: #8c969f; stroke-width: 1.8; }
.anim .code.c3 .cbox { stroke: #8e4787; stroke-width: 2.8; }
.anim .ctitle { fill: #17181a; font: 700 20px var(--display); text-anchor: middle; }
.anim .local-base { fill: #c7cacf; }
.anim .empty-slot { fill: #fff; stroke: #fff; stroke-width: 2; opacity: 0; }
.anim .local-chart { transform-box: fill-box; transform-origin: center; }
.anim .import-chart { opacity: 0; }

.anim .libbox { fill: #d9dbdd; stroke: #17181a; stroke-width: 2.2; }
.anim .libtitle { fill: #17181a; font: 700 21px var(--display); text-anchor: middle; }
.anim .lsub { font-style: italic; }

.anim .chip { stroke-width: 1.2; }
.anim .chip.ui    { fill: #cfe4f5; stroke: #6ba8c6; }
.anim .chip.state { fill: #f8ded0; stroke: #cf8f6c; }
.anim .chip.chart { fill: #c9edcf; stroke: #74b57c; }
.anim .chip.form  { fill: #f0d4ef; stroke: #b57cb0; }
.anim .chiplab { fill: #17181a; font: 650 15px var(--sans); text-anchor: middle; }

.anim .bubble { fill: #7c8087; }
.anim .req circle { fill: #fff; }
.anim .reqlab { fill: #17181a; font: 700 22px var(--display); }

.anim .flowB { fill: none; stroke: #23588f; stroke-width: 2.4; stroke-linecap: round; stroke-linejoin: round; }
.anim .hB { fill: #2b5f9e; }
.anim .codeflow { fill: none; stroke: #8e4787; stroke-width: 2.4; stroke-linecap: round; stroke-linejoin: round; }
.anim .hP { fill: #8e4787; }
.anim .flow-junction { fill: #23588f; }

.anim .phase { font: 700 24px var(--display); letter-spacing: .015em; }
.anim .phase-code, .anim .phase-cons { fill: #8e4787; text-anchor: end; }
.anim .phase-ex, .anim .phase-mi { fill: #2b5f9e; }
/* coding reads the library as it stands: dashed, to match the import convention */
.anim .flowR { fill: none; stroke: #2b5f9e; stroke-width: 2; stroke-linecap: round;
               stroke-dasharray: 5 4.4; }
.anim .refnote { fill: #2b5f9e; font: 650 17px var(--display); text-anchor: end; }
.anim .legend-title { fill: #737980; font: 750 11px var(--sans); letter-spacing: .07em; }
.anim .legend-label { fill: #2f3337; font: 650 15px var(--sans); }
.anim .legend-import { fill: #fff; stroke: #4a4d52; stroke-width: 1.8; stroke-dasharray: 4 3; }
.anim .legend-local { fill: #c7cacf; stroke: #aeb3b8; stroke-width: 1; }

/* --- state machine --- */
/* Every app owns ONE chip set. Migration restyles the shared chips in place, so a
   chip can never change colour between steps. Chips marked local stay solid.
   Timing rule: outgoing elements exit fast (.28s, no delay); incoming elements
   enter slower and slightly delayed, so steps never cross-fade into each other. */

.anim .code, .anim .req, .anim .codeflow, .anim .flowB, .anim .lchip,
.anim .flowR, .anim .refnote,
.anim .phase, .anim .chips, .anim .flow-junction,
.anim .empty-slot, .anim .chip {
  transition: opacity .28s ease, transform .45s ease, fill .45s ease,
              stroke-dasharray .45s ease, fill-opacity .45s ease;
}
.anim .code.c3, .anim .req, .anim .codeflow, .anim .flowB, .anim .l3,
.anim .flowR, .anim .refnote, .anim .phase,
.anim .flow-junction { opacity: 0; }
/* arrows rest slightly displaced against their travel direction */
.anim .codeflow, .anim .flowR { transform: translateY(-8px); }
.anim .up .flowB { transform: translateY(10px); }
.anim .down .flowB { transform: translateY(-10px); }

/* 1 — a request arrives */
.anim[data-step="1"] .req { opacity: 1; transition: opacity .5s ease .3s; }

/* 2 — coding turns the request into c3 with three repeated local blocks */
.anim[data-step="2"] .req { opacity: 1; }
/* both inputs first: the task request and the library as it stands */
.anim[data-step="2"] .codeflow,
.anim[data-step="2"] .phase-code,
.anim[data-step="2"] .flowR,
.anim[data-step="2"] .refnote {
  opacity: 1; transform: none;
  transition: opacity .35s ease .1s, transform .5s ease .1s;
}
/* then the code they produce */
.anim[data-step="2"] .code.c3 {
  opacity: 1;
  transition: opacity .5s ease .55s;
}

/* 3 — three local Chart blocks consolidate into one inside c3 */
.anim[data-step="3"] .code.c3 { opacity: 1; }
.anim[data-step="3"] .phase-cons { opacity: 1; transition: opacity .4s ease .1s; }
.anim[data-step="3"] .c3 .chart-2,
.anim[data-step="3"] .c3 .chart-3 {
  opacity: 0;
  transition: opacity .35s ease .45s, transform .6s ease .2s;
}
.anim[data-step="3"] .c3 .chart-2 { transform: translateX(-51px); }
.anim[data-step="3"] .c3 .chart-3 { transform: translateX(-102px); }
.anim[data-step="3"] .c3 .consolidate-hole {
  opacity: 1;
  transition: opacity .4s ease .65s;
}

/* 4 — the repeated component is extracted; the library gains Chart */
.anim[data-step="4"] .code.c3 { opacity: 1; }
.anim[data-step="4"] .phase-ex { opacity: 1; transition: opacity .4s ease .1s; }
.anim[data-step="4"] .up .flowB { opacity: 1; transform: none; }
.anim[data-step="4"] .flow-junction { opacity: 1; transition: opacity .35s ease .2s; }
.anim[data-step="4"] .up2 { transition: opacity .35s ease .15s, transform .55s ease .15s; }
.anim[data-step="4"] .up3 { transition: opacity .35s ease .25s, transform .55s ease .25s; }
.anim[data-step="4"] .upm { transition: opacity .35s ease .2s, transform .55s ease .2s; }
.anim[data-step="4"] .c3 .chart-2,
.anim[data-step="4"] .c3 .chart-3 {
  opacity: 0;
}
.anim[data-step="4"] .c3 .consolidate-hole {
  opacity: 1;
}
.anim[data-step="4"] .l3 { opacity: 1; transition: opacity .5s ease .85s; }

/* 5 — migration replaces local Chart code with imports */
.anim[data-step="5"] .c2 .local-chart,
.anim[data-step="5"] .c3 .local-chart {
  opacity: 0;
  transition: opacity .4s ease .35s, transform .5s ease .2s;
}
.anim[data-step="5"] .c2 .extract-hole,
.anim[data-step="5"] .c3 .empty-slot {
  opacity: 1;
  transition: opacity .45s ease .6s;
}
.anim[data-step="5"] .code.c3, .anim[data-step="5"] .l3 { opacity: 1; }
.anim[data-step="5"] .phase-mi { opacity: 1; transition: opacity .4s ease .1s; }
.anim[data-step="5"] .down .flowB { opacity: 1; transform: none; }
.anim[data-step="5"] .down .flowB:nth-of-type(1) { transition: opacity .35s ease .15s, transform .5s ease .15s; }
.anim[data-step="5"] .down .flowB:nth-of-type(2) { transition: opacity .35s ease .3s, transform .5s ease .3s; }
.anim[data-step="5"] .down .flowB:nth-of-type(3) { transition: opacity .35s ease .45s, transform .5s ease .45s; }
.anim[data-step="5"] .import-chart { opacity: 1; }
.anim .chip.imported,
.anim[data-step="5"] .chip.pending {
  stroke-dasharray: 3.5 2.5;
  stroke-width: 2;
  fill: #fff;
  fill-opacity: 1;
}
.anim[data-step="5"] .chip.pending {
  transition: opacity .28s ease, stroke-dasharray .5s ease .7s, fill-opacity .5s ease .7s;
}

.anim-steps {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 0.6rem;
  margin: 0.9rem 0 0;
  padding: 0;
}
.anim-steps li {
  position: relative;
  border-top: 2px solid var(--line);
  padding: 0.5rem 0.1rem 0;
  cursor: pointer;
  color: var(--ink-3);
}
.anim-steps li b { display: block; font-size: 1rem; color: var(--ink-2); }
.anim-steps li span { display: block; font-size: 0.9rem; line-height: 1.35; }
.anim-steps li:hover { border-top-color: var(--ink-3); }
.anim-steps li:hover b { color: var(--ink); }
.anim-steps li:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 4px; }
.anim-steps li.on { border-top-color: var(--accent-soft); }
.anim-steps li.on b { color: var(--accent); }
.anim-steps li.on span { color: var(--ink-2); }
/* dwell progress: fills the active item's top rule while autoplaying;
   sits still while paused (hover / click / off-screen) */
.anim-steps li.on::after {
  content: "";
  position: absolute;
  top: -2px; left: 0;
  height: 2px; width: 100%;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left center;
  animation: anim-dwell var(--dwell, 2600ms) linear forwards;
}
.anim.anim-paused .anim-steps li.on::after { animation-play-state: paused; }
@keyframes anim-dwell { from { transform: scaleX(0); } to { transform: scaleX(1); } }

.anim-hint {
  margin: 0.55rem 0 0;
  font-size: 0.78rem;
  color: var(--ink-3);
}

@media (max-width: 620px) { .anim-steps { grid-template-columns: repeat(2, 1fr); } }
@media (prefers-reduced-motion: reduce) {
  .anim svg *, .anim svg { transition: none !important; }
  .anim .codeflow, .anim .flowR, .anim .up .flowB, .anim .down .flowB { transform: none; }
  .anim-steps li.on::after { animation: none; transform: scaleX(1); }
  .anim-hint { visibility: hidden; }
}

/* ---------- library browser ---------- */

.browser {
  display: grid;
  grid-template-columns: minmax(230px, 300px) 1fr;
  gap: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--surface);
  margin-top: 1.6rem;
}
.tree {
  border-right: 1px solid var(--line);
  background: var(--surface-2);
  max-height: 30rem;
  overflow-y: auto;
  padding: 0.5rem 0;
}
.tree-group {
  font-size: 0.74rem;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--ink-3);
  padding: 0.7rem 1rem 0.3rem;
}
.tree button {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
  width: 100%;
  text-align: left;
  background: none;
  border: 0;
  border-left: 3px solid transparent;
  color: var(--ink-2);
  font: inherit;
  font-size: 0.87rem;
  padding: 0.32rem 1rem 0.32rem 0.85rem;
  cursor: pointer;
}
.tree button:hover { background: var(--surface); color: var(--ink); }
.tree button[aria-selected="true"] {
  background: var(--surface);
  color: var(--ink);
  border-left-color: var(--accent);
  font-weight: 600;
}
.tree .fname { font-family: var(--mono); font-size: 0.83rem; }
.reuse {
  margin-left: auto;
  font-size: 0.74rem;
  font-variant-numeric: tabular-nums;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 999px;
  padding: 0.05rem 0.45rem;
  white-space: nowrap;
}
.reuse.zero { color: var(--ink-3); background: var(--surface-2); }

.viewer { min-width: 0; display: flex; flex-direction: column; }
.viewer-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.7rem;
  padding: 0.7rem 1rem;
  border-bottom: 1px solid var(--line);
  font-size: 0.85rem;
  color: var(--ink-3);
}
.viewer-head .fname { font-family: var(--mono); color: var(--ink); font-size: 0.85rem; }
.viewer-head .sym { margin-left: auto; }

pre {
  margin: 0;
  padding: 1rem;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: 0.795rem;
  line-height: 1.6;
  tab-size: 2;
  max-height: 26rem;
}
code { font-family: var(--mono); }

/* minimal token colors */
.t-com { color: var(--ink-3); font-style: italic; }
.t-str { color: var(--add); }
.t-key { color: var(--accent); font-weight: 600; }
.t-tag { color: var(--del); }
.t-num { color: var(--del); }

/* ---------- before / after ---------- */

.ba {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--surface);
  margin-top: 1.2rem;
}
.ba-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.8rem;
  padding: 0.7rem 1rem;
  border-bottom: 1px solid var(--line);
  font-size: 0.85rem;
  color: var(--ink-3);
}
.ba-head .fname { font-family: var(--mono); color: var(--ink); }
/* its children join .ba-head's flex row, so .drop's margin-left:auto works */
#diff-meta { display: contents; }
.ba-head b { color: var(--ink); font-variant-numeric: tabular-nums; font-weight: 600; }
.ba-head .drop {
  margin-left: auto;
  font-weight: 700;
  font-size: 1rem;
  color: var(--accent);
  font-variant-numeric: tabular-nums;
}
.ba-cols { display: grid; grid-template-columns: 1fr 1fr; }
.ba-col { min-width: 0; border-left: 1px solid var(--line); }
.ba-col:first-child { border-left: 0; }
.ba-label {
  padding: 0.45rem 1rem;
  font-size: 0.76rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-3);
  background: var(--surface-2);
  border-bottom: 1px solid var(--line);
}
.ba-after .ba-label { color: var(--accent); background: var(--accent-soft); }
.ba-col pre { max-height: 32rem; font-size: 0.755rem; padding: 0.6rem 0; }
/* the code element sizes to its widest line, so every row's highlight spans the
   full scrollable width instead of stopping at the visible edge */
.ba-col pre > code { display: inline-block; min-width: 100%; }
.ln {
  display: block;
  white-space: pre;
  padding: 0 1rem 0 0;
}
.ln i {
  display: inline-block;
  width: 2.4rem;
  padding-right: 0.7rem;
  text-align: right;
  color: var(--ink-3);
  opacity: 0.55;
  font-style: normal;
  user-select: none;
}
.ln.del { background: var(--del-bg); }
.ln.add { background: var(--add-bg); }
.ln.fold {
  padding: 0.25rem 1rem 0.25rem 3.1rem;
  color: var(--ink-3);
  background: var(--surface-2);
  font-style: italic;
  border-top: 1px dashed var(--line);
  border-bottom: 1px dashed var(--line);
  margin: 0.15rem 0;
}

/* ---------- tables ---------- */

.table-scroll { overflow-x: auto; margin-top: 1.4rem; }
table {
  border-collapse: collapse;
  width: 100%;
  min-width: 640px;
  font-size: 0.88rem;
  font-variant-numeric: tabular-nums;
}
caption {
  caption-side: bottom;
  text-align: left;
  color: var(--ink-3);
  font-size: 0.85rem;
  line-height: 1.6;
  padding-top: 0.7rem;
}
th, td { padding: 0.45rem 0.7rem; text-align: right; }
th:first-child, td:first-child { text-align: left; white-space: nowrap; }
thead th {
  border-bottom: 1px solid var(--ink-3);
  font-weight: 600;
  color: var(--ink-2);
}
/* group header row: an underline that spans exactly the group's columns, so
   the reader can see which metrics sit under Functionality vs Maintainability */
thead tr:first-child th {
  font-size: 0.75rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-3);
  border-bottom: 0;
  padding-bottom: 0.15rem;
}
thead tr:first-child th.grp {
  text-align: center;
  color: var(--accent);
  font-weight: 650;
  border-bottom: 2px solid var(--accent);
  background: var(--accent-soft);
  border-top-left-radius: 5px;
  border-top-right-radius: 5px;
}
/* vertical rule where one group ends and the next begins */
th.gstart, td.gstart { border-left: 1px solid var(--line); }
thead tr:first-child th.gstart { border-left: 0; }
th.gstart, td.gstart { padding-left: 0.95rem; }
tbody tr { border-bottom: 1px solid var(--line); }
tbody tr.ours { background: var(--accent-soft); }
tbody tr.ours td { font-weight: 600; }
td.best { color: var(--accent); font-weight: 700; }
tbody tr.delta { color: var(--ink-3); font-style: italic; }
tbody tr.delta td { border-top: 1px solid var(--line); }

.tabs { display: flex; gap: 0.4rem; margin-top: 1.4rem; }
.tabs button {
  font: inherit;
  font-size: 0.88rem;
  padding: 0.35rem 0.9rem;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink-2);
  cursor: pointer;
}
.tabs button[aria-selected="true"] {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--bg);
}

/* ---------- misc ---------- */

.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 2rem; }
.two-col.split { align-items: stretch; gap: 1.6rem; margin: 1.4rem 0 1.8rem; }
.two-col.split .fig-flush { display: flex; flex-direction: column; justify-content: center; }
.payoff {
  display: flex;
  flex-direction: column;
  justify-content: center;
}
.payoff-head {
  margin: 0 0 0.8rem;
  font-size: 0.75rem;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  font-weight: 650;
  color: var(--accent);
}
/* a vertical ledger reads better beside a wide figure than a 2x2 grid */
.ledger { list-style: none; margin: 0; padding: 0; }
.ledger li {
  display: flex;
  align-items: baseline;
  gap: 1.1rem;
  padding: 0.85rem 0;
  border-top: 1px solid var(--line);
}
.ledger li:first-child { border-top: 0; padding-top: 0; }
.ledger li > b {
  flex: 0 0 6.2rem;
  text-align: right;
  font-size: clamp(1.35rem, 2.1vw, 1.75rem);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
  color: var(--accent);
}
.ledger li.parity > b { color: var(--ink-2); font-size: clamp(1.1rem, 1.6vw, 1.35rem); }
.ledger li > span { display: block; font-size: 0.86rem; color: var(--ink-3); }
.ledger li em {
  display: block;
  font-style: normal;
  font-size: 1rem;
  color: var(--ink);
  margin-bottom: 0.1rem;
}
.ledger li i { font-style: normal; font-variant-numeric: tabular-nums; }
.payoff-foot {
  margin: 0.85rem 0 0;
  font-size: 0.78rem;
  line-height: 1.45;
  color: var(--ink-3);
}

/* the table carries the detail here, so give it the wider column */
.two-col.abs { grid-template-columns: 0.78fr 1.22fr;
               align-items: start; gap: 1.6rem; margin-top: 1.4rem; }
.two-col.abs .table-scroll {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  overflow-x: auto;
}
.two-col.abs table { width: 100%; }
.two-col.abs table { min-width: 0; width: 100%; font-size: 0.83rem; table-layout: fixed; }
.two-col.abs thead th {
  overflow-wrap: anywhere;
  background: var(--surface-2);
  color: var(--ink);
  font-weight: 650;
  font-size: 0.74rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding: 0.6rem 0.8rem;
  border-bottom: 1px solid var(--ink-3);
  vertical-align: bottom;
}
.two-col.abs tbody td { padding: 0.6rem 0.6rem; overflow-wrap: anywhere; }
.two-col.abs tbody tr:last-child { border-bottom: 0; }
.two-col.abs tbody td:first-child { font-weight: 600; color: var(--ink); }
.two-col.abs td.sym code {
  display: block;
  font-size: 0.74rem;
  color: var(--ink-2);
  overflow-wrap: anywhere;
}
.two-col.abs tr.ours td.sym code { color: var(--ink); }
.two-col.abs td, .two-col.abs th { text-align: left; vertical-align: top; }
.two-col.abs caption { padding: 0.7rem 0.8rem 0.8rem; margin: 0; }

.cause {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  padding: 1.1rem 1.2rem 1rem;
}
.cause-tag {
  font-size: 0.72rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin: 0 0 0.35rem;
}
.cause > b { display: block; font-size: 1rem; margin-bottom: 0.4rem; }
.cause p { font-size: 0.93rem; color: var(--ink-2); margin: 0; max-width: none; }
ul.plain { max-width: none; padding-left: 1.1rem; color: var(--ink-2); }
ul.plain li { margin-bottom: 0.5rem; }
ul.plain b { color: var(--ink); }

.bibtex-wrap { position: relative; margin-top: 1.2rem; }
.bibtex-wrap pre {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  max-height: none;
}
.copy {
  position: absolute;
  top: 0.6rem;
  right: 0.6rem;
  font: inherit;
  font-size: 0.8rem;
  padding: 0.3rem 0.7rem;
  border-radius: 6px;
  border: 1px solid var(--line);
  background: var(--bg);
  color: var(--ink-2);
  cursor: pointer;
}
.copy:hover { color: var(--accent); border-color: var(--accent); }

/* ---------- responsive ---------- */

@media (max-width: 900px) {
  .hero-hook { white-space: normal; text-wrap: balance; }
  .formula-stack,
  .experiment-grid { grid-template-columns: 1fr; }
  .formula-block.formula-goal { grid-column: auto; }
  .challenge-row { grid-template-columns: 1fr; gap: 0.9rem; }
  .two-col.split { gap: 1.2rem; }
  .ba-cols { grid-template-columns: 1fr; }
  .ba-col { border-left: 0; border-top: 1px solid var(--line); }
  .pipeline { grid-template-columns: repeat(2, 1fr); }
  .pipeline li + li::before { display: none; }
  .browser { grid-template-columns: 1fr; }
  .tree { border-right: 0; border-bottom: 1px solid var(--line); max-height: 14rem; }
  .two-col { grid-template-columns: 1fr; gap: 1.2rem; }
  /* the widened abstraction split must collapse like every other two-col */
  .two-col.abs { grid-template-columns: 1fr; }
  .two-col.abs .table-scroll { overflow-x: auto; }
  /* wide enough that the symbol names stay whole; the box scrolls */
  .two-col.abs table { min-width: 35rem; }
  .two-col.abs tbody td { overflow-wrap: normal; }
}

@media (max-width: 620px) {
  body { font-size: 16px; }
  .hero { padding-top: 3.25rem; }
  .hero-proof { grid-template-columns: 1fr; }
  .hero-stats {
    grid-template-columns: 1fr;
    padding-right: 0;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }
  .hero-stats > div { display: flex; padding: 0.85rem 1rem; text-align: left; }
  .hero-stats strong { font-size: 1.75rem; }
  .notation dl > div { grid-template-columns: 4rem 1fr; }
  .formula-block { grid-template-columns: 1fr; gap: 0.35rem; }
  .equation { text-align: left; }
  .mapping { grid-template-columns: 1fr; gap: 0.6rem; }
  .rail { text-align: left; padding-top: 0.6rem; }
  .rail-arrow { display: none; }
  .arrow { text-align: left; }
  .arrow + .arrow { display: none; }
  .pipeline { grid-template-columns: 1fr; }
  .nav-links { gap: 0.85rem; font-size: 0.84rem; }
  .nav-mark { display: none; }
  section { padding: 2.5rem 0; }

  /* the link row scrolls; fade the trailing edge so it reads as scrollable
     rather than truncated, and keep the last item off the screen edge */
  .nav-inner { padding-left: 1rem; padding-right: 0; }
  .nav-links { padding-right: 1rem; scrollbar-width: none; }
  .nav-links::-webkit-scrollbar { display: none; }
  .nav-links {
    -webkit-mask-image: linear-gradient(to right, #000 calc(100% - 1.6rem), transparent);
            mask-image: linear-gradient(to right, #000 calc(100% - 1.6rem), transparent);
  }

  /* a caption inside a horizontally scrolling table inherits the table's
     width and gets clipped; pin it to the viewport instead */
  .table-scroll caption {
    position: sticky;
    left: 0;
    width: calc(var(--page) - 3rem);
    box-sizing: border-box;
  }

  /* centred text reads as ragged once the lines are this short */
  figcaption { text-align: left; }
  .anim-steps li { text-align: left; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}