@font-face {
  font-family: PageSerif;
  src: local("Iowan Old Style"), local("Palatino");
  font-display: swap;
}

:root {
  --ink: #1f2329;
  --soft: #50565f;
  --muted: #747b86;
  --accent: #3063ca;
  --accent-deep: #234c9e;
  --accent-pale: #edf3fc;
  --paper: #f7f9fc;
  --line: #e3e7ee;
  --pre: #3b4250;
  --fa: #e3394a;
  --hc: #7540c8;
  --serif: PageSerif, "Palatino Linotype", Georgia, serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: 76px;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  color: var(--ink);
  background: #fff;
  font: 18px/1.7 var(--serif);
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 4px; }
button, input { font: inherit; }
button { cursor: pointer; }
a:focus-visible, button:focus-visible, input:focus-visible, summary:focus-visible {
  outline: 3px solid #7fa3e6;
  outline-offset: 4px;
}

svg { fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; }
.button svg { width: 17px; height: 17px; }

h1, h2, h3, p, figure { margin: 0; }
p + p { margin-top: 18px; }
h1, h2, h3 { font-weight: 600; }
h2 { font-size: clamp(28px, 3.3vw, 36px); line-height: 1.22; letter-spacing: -.025em; margin-bottom: 26px; }
h3 { font-size: 23px; line-height: 1.35; margin-bottom: 14px; }
strong { font-weight: 700; }
sup { font-size: .65em; margin-left: 2px; }
.nowrap { white-space: nowrap; }

.skip-link { position: absolute; left: -999px; top: 8px; background: #fff; padding: 8px 14px; z-index: 50; }
.skip-link:focus { left: 8px; }

.container { max-width: 1136px; padding: 0 32px; margin: 0 auto; }
.narrow { max-width: 820px; padding: 0 32px; margin: 0 auto; }
.reading-width { max-width: 780px; }
.spaced { margin-top: 56px; }

/* ---------- hero ---------- */
.hero {
  text-align: center;
  padding: 64px 0 44px;
  background: radial-gradient(ellipse at 50% 0, rgba(48, 99, 202, .07), transparent 70%);
}
.eyebrow {
  display: inline-flex; gap: 10px; align-items: center;
  border: 1px solid #d8e3f6; background: #f1f6fd;
  padding: 5px 14px; border-radius: 20px;
  color: var(--accent); font: 500 11px/1.8 var(--sans);
  letter-spacing: .14em; text-transform: uppercase; margin-bottom: 26px;
}
.eyebrow span { opacity: .5; }
.brandline {
  display: flex; justify-content: center; align-items: center; gap: 14px;
  font: 700 46px/1 var(--sans); letter-spacing: -.03em; margin-bottom: 18px;
}
.brandline img { height: 52px; width: auto; }
.brandline b, .nav-brand b { color: var(--accent); font-weight: inherit; }
h1 { font-size: clamp(30px, 3.9vw, 45px); line-height: 1.18; letter-spacing: -.026em; }
h1 em { color: var(--accent); font-weight: 500; }
.subtitle { font-size: 21px; line-height: 1.5; color: var(--soft); margin: 22px auto 0; }
.authors { display: flex; flex-wrap: wrap; justify-content: center; gap: 7px 24px; margin: 28px auto 7px; font-size: 17px; max-width: 860px; }
.authors span { white-space: nowrap; }
.authors .author-break { flex-basis: 100%; height: 0; margin-top: -7px; }
.affiliations { display: flex; justify-content: center; flex-wrap: wrap; gap: 6px 22px; color: var(--soft); font: 13px/1.65 var(--sans); }
.author-note { font: 12px/1.5 var(--sans); color: var(--muted); margin-top: 9px; }
.resource-links { display: flex; justify-content: center; flex-wrap: wrap; gap: 10px; margin-top: 29px; }
.button {
  display: inline-flex; align-items: center; gap: 9px;
  font: 500 13px/1.4 var(--sans);
  border: 1px solid var(--line); padding: 11px 18px; border-radius: 24px;
  background: #fff; color: var(--ink);
  transition: transform .15s, background .15s;
}
.button:hover { transform: translateY(-2px); background: var(--paper); text-decoration: none; }
.button.primary { background: var(--ink); border-color: var(--ink); color: #fff; }
.button.primary:hover { background: var(--accent); border-color: var(--accent); }
.emoji { font-size: 15px; line-height: 1; }

/* ---------- nav ---------- */
.section-nav {
  position: sticky; top: 0; z-index: 10;
  border-block: 1px solid var(--line);
  background: rgba(255, 255, 255, .96); backdrop-filter: blur(14px);
  font: 12px/1.5 var(--sans);
}
.nav-inner {
  max-width: 1136px; padding: 0 32px; margin: auto;
  display: flex; align-items: center; justify-content: space-between;
  min-height: 59px; gap: 24px;
}
.nav-brand { display: inline-flex; align-items: center; gap: 8px; font: 700 19px/1 var(--sans); letter-spacing: -.02em; color: var(--ink); }
.nav-brand:hover { text-decoration: none; }
.nav-brand img { height: 22px; width: auto; }
.nav-links { display: flex; gap: 26px; overflow-x: auto; scrollbar-width: none; }
.nav-links a { display: block; padding: 20px 0; color: var(--soft); white-space: nowrap; border-bottom: 2px solid transparent; }
.nav-links a:hover, .nav-links a[aria-current="location"] { color: var(--accent); border-color: var(--accent); text-decoration: none; }

/* ---------- figures ---------- */
.teaser { padding-top: 40px; }
.figure-card {
  border: 1px solid var(--line); border-radius: 9px; background: #fff;
  padding: 23px 24px; margin: 30px 0 0;
  box-shadow: 0 2px 8px rgba(20, 30, 60, .03);
}
.teaser .figure-card { margin: 0; }
.figure-topline { display: flex; align-items: center; justify-content: space-between; gap: 14px; margin-bottom: 20px; flex-wrap: wrap; }
.small-label, .section-label { font: 600 11px/1.5 var(--sans); letter-spacing: .13em; text-transform: uppercase; color: var(--accent); }
.figure-topline .small-label { color: var(--muted); font-size: 10px; letter-spacing: .1em; }
.figure-topline > a { font: 11px/1.5 var(--sans); white-space: nowrap; color: var(--muted); }
.figure-zoom { display: block; cursor: zoom-in; border-radius: 3px; }
.figure-zoom img, .teaser-video { display: block; width: 100%; height: auto; }
.teaser-video { border-radius: 6px; background: var(--paper); aspect-ratio: 2400 / 1060; }
figcaption { color: var(--soft); font: 13px/1.7 var(--sans); margin: 20px auto 0; max-width: 860px; }
figcaption strong { color: var(--ink); }
figcaption p + p { margin-top: 10px; }

.study-strip { display: grid; grid-template-columns: repeat(4, 1fr); padding: 30px 0 33px; border-bottom: 1px solid var(--line); text-align: center; }
.study-strip > div + div { border-left: 1px solid var(--line); }
.study-strip strong { display: block; font-size: 25px; font-weight: 500; }
.study-strip span { display: block; font: 11px/1.6 var(--sans); color: var(--muted); margin-top: 3px; }

/* ---------- sections ---------- */
section { padding: 68px 0; }
section + section { border-top: 1px solid var(--line); }
.section-label { margin-bottom: 14px; }
.soft-section { background: var(--paper); }
.tldr { border-left: 3px solid var(--accent); padding: 22px 27px; background: var(--paper); margin-bottom: 30px; border-radius: 0 6px 6px 0; }
.tldr p { margin-top: 8px; font-size: 18px; }

.finding-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 28px; margin-top: 34px; }
.finding { display: flex; flex-direction: column; border-top: 1px solid #c9d6ee; padding-top: 21px; }
.finding-number { font: 11px/1.5 var(--sans); color: var(--accent); letter-spacing: .08em; margin-bottom: 17px; }
.finding h3 { font-size: 22px; }
.finding p { font-size: 16px; line-height: 1.65; color: var(--soft); margin-bottom: 24px; }
.finding > a { margin-top: auto; font: 500 12px/1.5 var(--sans); }
.finding > a span { margin-left: 4px; }

/* ---------- shape explorer ---------- */
.shape-demo { border: 1px solid var(--line); border-radius: 10px; padding: 26px 32px; background: #fff; margin-top: 34px; }
.shape-body { display: grid; grid-template-columns: 360px 1fr; gap: 40px; align-items: end; margin-top: 18px; }
#shape-stack { width: 100%; height: auto; }
.shape-stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px 18px; font-family: var(--sans); padding-bottom: 6px; }
.shape-stats span { display: block; font-size: 11px; color: var(--muted); letter-spacing: .06em; text-transform: uppercase; }
.shape-stats strong { display: block; font-size: 30px; font-weight: 600; font-variant-numeric: tabular-nums; letter-spacing: -.01em; }
.shape-stats .accent { color: var(--accent); }
.slider-row { display: flex; align-items: center; gap: 18px; margin-top: 26px; padding-top: 22px; border-top: 1px solid var(--line); font: 12px/1.4 var(--sans); color: var(--muted); }
.slider-end { white-space: nowrap; }
input[type="range"] { flex: 1; accent-color: var(--accent); height: 22px; }
.demo-note { font: 12px/1.6 var(--sans); color: var(--muted); margin-top: 14px; }

.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 44px; margin-top: 44px; }
.two-col p { font-size: 16px; color: var(--soft); }

.formula-box { border: 1px solid var(--line); border-radius: 9px; background: #fff; padding: 22px 28px 24px; margin-top: 34px; text-align: center; }
.soft-section .formula-box { background: #fff; }
section:not(.soft-section) .formula-box { background: var(--paper); }
.formula-box .small-label { margin-bottom: 4px; }
.formula-box.two { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
.math-display { font-size: 19px; overflow-x: auto; overflow-y: hidden; }
.formula-note { font: 13px/1.6 var(--sans); color: var(--muted); }

.table-title { margin-top: 52px; }
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: 9px; background: #fff; }
table { width: 100%; border-collapse: collapse; font: 14px/1.5 var(--sans); }
th { text-align: left; font-weight: 500; font-size: 12px; color: var(--muted); padding: 13px 18px; border-bottom: 1px solid var(--line); white-space: nowrap; }
td { padding: 11px 18px; border-bottom: 1px solid var(--line); vertical-align: middle; }
tr:last-child td { border-bottom: 0; }
.arch-table td.fam { color: var(--muted); font-size: 12px; }
.arch-table td.m { font-weight: 600; white-space: nowrap; }
.arch-table td.math { font-size: 13px; }
.arch-table tr.group-start td { border-top: 1px solid #d3dbe8; }
.arch-table td[rowspan] { border-right: 1px solid var(--line); }

.table-card { border: 1px solid var(--line); border-radius: 9px; overflow: hidden; background: #fff; margin-top: 30px; }
.table-head { background: #eef2f8; padding: 13px 18px; font: 12px/1.5 var(--sans); color: var(--soft); border-bottom: 1px solid var(--line); }
.num { text-align: right; font-variant-numeric: tabular-nums; }
tr.highlight td { background: var(--accent-pale); color: var(--accent-deep); font-weight: 600; }

.stat-row { display: grid; grid-template-columns: repeat(3, 1fr); margin: 40px 0 6px; text-align: center; }
.stat-row > div + div { border-left: 1px solid var(--line); }
.stat-row strong { display: block; font-size: 36px; font-weight: 500; color: var(--accent); letter-spacing: -.02em; line-height: 1.2; }
.stat-row span { display: block; font: 12px/1.6 var(--sans); color: var(--soft); margin-top: 8px; padding: 0 12px; }

/* ---------- interactive chart ---------- */
.chart-card #loss-chart { width: 100%; max-width: 760px; height: auto; display: block; margin: 0 auto; font-family: var(--sans); }
.seg { display: inline-flex; border: 1px solid var(--line); border-radius: 18px; padding: 3px; background: var(--paper); }
.seg button { border: 0; background: transparent; padding: 5px 13px; border-radius: 14px; font: 500 12px/1.4 var(--sans); color: var(--soft); }
.seg button[aria-pressed="true"] { background: #fff; color: var(--accent); box-shadow: 0 1px 3px rgba(20, 30, 60, .12); }
.view-switch { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px 26px; margin: -4px 0 14px; }
.seg-group { display: flex; align-items: center; gap: 10px; }
.seg-label { font: 600 10px/1.4 var(--sans); letter-spacing: .1em; text-transform: uppercase; color: var(--muted); }
.legend button[hidden] { display: none; }
.chart-hint {
  display: flex; align-items: center; justify-content: center; gap: 8px; width: fit-content; margin: 16px auto 0;
  padding: 7px 16px; border-radius: 18px; background: var(--accent-pale); border: 1px solid #d3e0f7;
  font: 500 13px/1.4 var(--sans); color: var(--accent-deep);
}
.chart-hint svg { width: 16px; height: 16px; flex: none; }
.chart-points { margin: 0 auto; padding-left: 20px; max-width: 860px; }
.chart-points li + li { margin-top: 6px; }
.legend { display: flex; flex-direction: column; align-items: center; gap: 8px; margin-top: 14px; }
.legend-row { display: flex; flex-wrap: wrap; justify-content: center; gap: 8px 10px; }
.legend-row:not(:has(button:not([hidden]))) { display: none; }
.legend button {
  display: inline-flex; align-items: center; gap: 8px;
  border: 1px solid var(--line); background: #fff; border-radius: 16px;
  padding: 5px 12px; font: 12px/1.4 var(--sans); color: var(--muted);
  transition: color .15s, border-color .15s, background .15s;
}
.legend button i { width: 14px; height: 3px; border-radius: 2px; background: var(--c); opacity: .35; }
.legend button[aria-pressed="true"] { color: var(--ink); border-color: var(--c); background: #fff; }
.legend button[aria-pressed="true"] i { opacity: 1; }
#loss-chart .line { fill: none; stroke-width: 2; stroke-linejoin: round; stroke-linecap: round; transition: opacity .2s, stroke-width .2s; }
#loss-chart .line.on { stroke-width: 3.4; }
#loss-chart .dot { transition: opacity .2s; }
#loss-chart .grid { stroke: #e9edf3; stroke-width: 1; }
#loss-chart .tick { fill: var(--muted); font-size: 12px; }
#loss-chart .tick2 { fill: #9aa2ae; font-size: 10.5px; }
#loss-chart .axis-label { fill: var(--soft); font-size: 12.5px; }

/* ---------- disclosure ---------- */
.disclosure { margin-top: 30px; border: 1px solid var(--line); border-radius: 9px; background: #fff; }
.disclosure summary { list-style: none; display: flex; justify-content: space-between; align-items: center; padding: 18px 22px; font: 500 14px/1.5 var(--sans); cursor: pointer; }
.disclosure summary::-webkit-details-marker { display: none; }
.disclosure summary span { color: var(--accent); font-size: 18px; transition: transform .2s; }
.disclosure[open] summary span { transform: rotate(45deg); }
.disclosure-body { padding: 0 22px 24px; }
.disclosure-body p { font-size: 16px; color: var(--soft); margin-top: 18px; }
.disclosure-body .figure-card { margin-top: 18px; box-shadow: none; }

/* ---------- takeaway ---------- */
.takeaway-section { padding: 76px 0; background: radial-gradient(ellipse at 50% 100%, rgba(48, 99, 202, .07), transparent 70%); }
.takeaway { text-align: center; }
.takeaway .small-label { margin-bottom: 18px; font-size: 12px; }
.takeaway-text { font-size: clamp(24px, 2.7vw, 31px); line-height: 1.42; letter-spacing: -.015em; font-weight: 600; }

/* ---------- resources ---------- */
.resource-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.resource { display: flex; flex-direction: column; gap: 6px; border: 1px solid var(--line); border-radius: 9px; background: #fff; padding: 22px 24px; color: var(--ink); transition: transform .15s, border-color .15s; }
.resource:hover { transform: translateY(-2px); border-color: #b9cbec; text-decoration: none; }
.resource-icon { color: var(--accent); height: 26px; display: flex; align-items: center; }
.resource-icon svg { width: 22px; height: 22px; }
.emoji-icon { font-size: 21px; }
.resource strong { font: 600 17px/1.4 var(--sans); }
.resource span:last-child { font: 13px/1.6 var(--sans); color: var(--muted); }
.code-card { margin-top: 24px; border: 1px solid var(--line); border-radius: 9px; overflow: hidden; background: #fff; }
.code-head { background: #eef2f8; padding: 11px 18px; font: 12px/1.5 var(--sans); color: var(--soft); border-bottom: 1px solid var(--line); }
pre { margin: 0; overflow-x: auto; font: 13px/1.7 var(--mono); }
.code-card pre { padding: 18px 20px; color: #2b3240; }

/* ---------- citation ---------- */
.bibtex-card { position: relative; border: 1px solid var(--line); border-radius: 9px; background: var(--paper); padding: 50px 24px 18px; }
.bibtex-card pre { font-size: 12.5px; color: #2b3240; white-space: pre; }
#copy-citation { position: absolute; top: 14px; right: 14px; border: 1px solid var(--line); background: #fff; border-radius: 16px; padding: 6px 14px; font: 500 12px/1.4 var(--sans); color: var(--ink); }
#copy-citation:hover { border-color: var(--accent); color: var(--accent); }
.copy-status { font: 12px/1.5 var(--sans); color: var(--muted); margin-top: 8px; min-height: 18px; }

/* ---------- footer ---------- */
.footer { border-top: 1px solid var(--line); padding: 30px 0 40px; }
.footer-inner { display: flex; justify-content: space-between; align-items: center; gap: 20px; flex-wrap: wrap; }
.footer p { font: 12px/1.6 var(--sans); color: var(--muted); }

/* ---------- lightbox ---------- */
dialog { border: 0; padding: 0; border-radius: 10px; width: min(1400px, 94vw); max-height: 92vh; box-shadow: 0 20px 60px rgba(0, 0, 0, .25); }
dialog::backdrop { background: rgba(15, 20, 30, .55); }
.dialog-bar { display: flex; justify-content: space-between; align-items: center; padding: 12px 18px; border-bottom: 1px solid var(--line); font: 13px/1.4 var(--sans); color: var(--soft); }
.dialog-bar button { border: 0; background: transparent; font-size: 16px; color: var(--soft); }
.dialog-image-wrap { overflow: auto; max-height: calc(92vh - 50px); padding: 16px; }
.dialog-image-wrap img { display: block; width: 100%; height: auto; }
body.modal-open { overflow: hidden; }

/* ---------- responsive ---------- */
@media (max-width: 980px) {
  .finding-grid { grid-template-columns: 1fr 1fr; }
  .shape-body { grid-template-columns: 1fr; gap: 24px; }
  #shape-stack { max-width: 360px; margin: 0 auto; display: block; }
}
@media (max-width: 760px) {
  body { font-size: 17px; }
  .container, .narrow, .nav-inner { padding: 0 18px; }
  .desktop-break { display: none; }
  .brandline { font-size: 36px; }
  .brandline img { height: 40px; }
  .subtitle { font-size: 18px; }
  .nav-brand { display: none; }
  .study-strip { grid-template-columns: 1fr 1fr; gap: 18px 0; }
  .study-strip > div:nth-child(3) { border-left: 0; }
  .finding-grid, .two-col, .resource-grid, .formula-box.two { grid-template-columns: 1fr; }
  .stat-row { grid-template-columns: 1fr; gap: 20px; }
  .stat-row > div + div { border-left: 0; border-top: 1px solid var(--line); padding-top: 20px; }
  .shape-demo { padding: 20px 18px; }
  .shape-stats { grid-template-columns: 1fr 1fr; }
  .shape-stats strong { font-size: 24px; }
  .slider-row { flex-wrap: wrap; justify-content: space-between; }
  .slider-row input { order: -1; flex-basis: 100%; }
  .view-switch { flex-direction: column; align-items: stretch; gap: 10px; }
  .seg-group { flex-direction: column; align-items: flex-start; gap: 6px; }
  .seg { flex-wrap: wrap; }
  .seg button { white-space: nowrap; }
  .figure-card { padding: 16px; }
  section { padding: 52px 0; }
  .math-display { font-size: 16px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .button, .resource { transition: none; }
}

/* keep KaTeX's visually-hidden MathML inside scrollable containers */
.table-wrap, .math-display, .table-card, td.math { position: relative; }