/* InterSim project page
   Colors: Purdue palette for accents; orange/blue match the paper's architecture figure
   (digital twin cycle / HITL cycle); chart colors match the paper's plots. */

:root {
  --ink: #17191e;
  --ink-2: #3a3f49;
  --muted: #646b78;
  --line: #e3e5ea;
  --bg: #ffffff;
  --bg-soft: #f6f6f3;
  --card: #ffffff;

  --gold: #cfb991;        /* Purdue Boilermaker Gold */
  --gold-soft: #f3ecdd;
  --aged: #8e6f3e;        /* Purdue Aged, link/accent text */

  --dt: #ef8a24;          /* digital twin cycle (figure orange) */
  --dt-soft: #fdf1e4;
  --hitl: #2f86d6;        /* HITL cycle (figure blue) */
  --hitl-soft: #e8f2fc;

  --rci: #3b75af;         /* chart: RCI / human (paper plots) */
  --std: #ef8636;         /* chart: standard / agent */
  --good: #2f7d4f;
  --warn: #b5541c;

  --radius: 12px;
  --shadow: 0 1px 2px rgba(20, 24, 31, .06), 0 4px 16px rgba(20, 24, 31, .05);
  --font: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 72px; -webkit-text-size-adjust: 100%; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

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

img, video { max-width: 100%; height: auto; display: block; }
a { color: var(--aged); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }
em { font-style: italic; }
sup, sub { line-height: 0; }

.wrap { max-width: 1040px; margin: 0 auto; padding: 0 24px; }
.wrap.wide { max-width: 1200px; }
.wrap.narrow, .narrow { max-width: 780px; }
.wrap.narrow { margin: 0 auto; }
p.narrow, .section-intro.narrow { margin-left: auto; margin-right: auto; }

/* ---------- top bar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 50;
  background: #111317; border-bottom: 3px solid var(--gold);
}
.topbar-inner {
  max-width: 1200px; margin: 0 auto; padding: 0 24px;
  height: 60px; display: flex; align-items: center; justify-content: space-between; gap: 24px;
}
.wordmark { font-weight: 700; color: #fff; letter-spacing: -.01em; font-size: 22px; }
.wordmark:hover { text-decoration: none; color: var(--gold); }
.lab-link { font-size: 16px; font-weight: 600; color: var(--gold); white-space: nowrap; }
.lab-link:hover { color: #fff; text-decoration: none; }

/* ---------- hero ---------- */
.hero { padding: 64px 0 28px; text-align: center; }
.hero h1 {
  margin: 0 auto 22px; max-width: 1100px;
  font-size: clamp(26px, 3.6vw, 44px); line-height: 1.18; font-weight: 700; letter-spacing: -.02em;
}
/* three lines: "InterSim:" / "Innovative Intersection Digital Twins for" / "Human-in-the-Loop Driving Simulation" */
.hero h1 .title-line { display: block; text-wrap: balance; }
.hero h1 .accent { color: var(--aged); }
.authors { margin: 0 auto 8px; max-width: 860px; font-size: 18px; line-height: 1.7; }
.authors a, .authors span { color: var(--ink); white-space: nowrap; }
.authors span { padding-bottom: 1px; }
.authors a { border-bottom: 1px solid var(--gold); }
.authors a:hover { text-decoration: none; border-bottom-color: var(--aged); }
.authors sup { font-size: 11px; color: var(--muted); margin-left: 1px; }
.affils {
  margin: 0 auto 26px; display: flex; flex-wrap: wrap; justify-content: center; gap: 4px 22px;
  color: var(--muted); font-size: 15px;
}
.affils sup { font-size: 10px; margin-right: 2px; }

.buttons { display: flex; flex-wrap: wrap; justify-content: center; gap: 10px; }
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 10px 18px; border-radius: 999px;
  background: var(--ink); color: #fff; font-weight: 600; font-size: 15px; line-height: 1;
  transition: background .15s ease, transform .15s ease;
}
.btn svg { width: 18px; height: 18px; }
.btn:hover { background: #2c3038; text-decoration: none; transform: translateY(-1px); }
.btn.is-soon { background: #e9eaee; color: var(--muted); cursor: default; }
.btn.is-soon:hover { transform: none; }
.btn .soon {
  font-size: 10px; font-weight: 700; text-transform: uppercase; letter-spacing: .06em;
  padding: 3px 6px; border-radius: 999px; background: #fff; color: var(--muted);
}

/* ---------- video under the title ---------- */
.teaser { padding: 18px 0 8px; }
.teaser .video-frame { max-width: 1100px; }
figcaption { margin-top: 10px; color: var(--muted); font-size: 14.5px; line-height: 1.5; text-align: center; }

/* ---------- sections ---------- */
.section { padding: 72px 0; }
.section.alt { background: var(--bg-soft); }
.section h2 {
  margin: 0 0 18px; text-align: center;
  font-size: clamp(24px, 3vw, 32px); line-height: 1.2; font-weight: 700; letter-spacing: -.015em;
}
.section h2::after {
  content: ""; display: block; width: 44px; height: 3px; margin: 14px auto 0; border-radius: 3px; background: var(--gold);
}
.section-intro { color: var(--ink-2); text-align: center; margin: 0 auto 28px; }
.subhead { margin: 52px 0 18px; text-align: center; font-size: 21px; font-weight: 650; letter-spacing: -.01em; }
.hint { color: var(--muted); font-size: 14.5px; margin: -6px 0 16px; text-align: center; }
#overview .abstract { text-align: justify; hyphens: auto; -webkit-hyphens: auto; }
.nowrap { white-space: nowrap; }

/* ---------- cards ---------- */
.cards { display: grid; gap: 18px; }
.cards.three { grid-template-columns: repeat(3, 1fr); }
.cards.two { grid-template-columns: repeat(2, 1fr); }
.card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 22px 22px 20px; box-shadow: var(--shadow);
}
.card h4 { margin: 2px 0 8px; font-size: 17.5px; line-height: 1.35; font-weight: 650; }
.card p { margin: 0; font-size: 15.5px; line-height: 1.6; color: var(--ink-2); }
.card .card-kicker {
  font-size: 12px; font-weight: 700; text-transform: uppercase; letter-spacing: .08em; color: var(--aged); margin-bottom: 4px;
}
.reasons .card { padding: 22px 22px 22px; border-top: 3px solid var(--gold); }
.reasons .card h4 { margin: 4px 0 0; font-size: 18.5px; line-height: 1.4; }
.reason-icon { display: block; width: 60px; height: 60px; margin-bottom: 14px; overflow: visible; }
.reason-icon .ri-bg { fill: var(--gold-soft); }
.reason-icon .ri-line, .reason-icon .ri-accent { fill: none; stroke-width: 2.4; stroke-linecap: round; stroke-linejoin: round; }
.reason-icon .ri-line { stroke: var(--ink); }
.reason-icon .ri-accent { stroke: var(--aged); }
.reason-icon .ri-dot { fill: var(--aged); }

/* ---------- architecture walkthrough ---------- */
.arch-section { padding-bottom: 40px; }
.arch-section .section-intro { margin-bottom: 20px; }
.arch-stage { position: relative; }
.arch-figure { position: relative; margin: 0 auto; }
.arch-figure img { width: 100%; border: 1px solid var(--line); border-radius: 10px; }
.arch-ov {
  position: absolute; background: rgba(255, 255, 255, .84); opacity: 0; pointer-events: none;
  transition: opacity .6s ease;
}
/* boxes measured on the 2400x1302 figure: analysis module ends at y=885, ego platform starts at y=941, legend starts at x=1980 */
.ov-dt { left: 0; top: 0; width: 100%; height: 70.1%; border-radius: 10px 10px 0 0; }
.ov-hitl { left: 0; top: 70.1%; width: 81.9%; bottom: 0; border-radius: 0 0 0 10px; }
.arch-note {
  border-radius: var(--radius); padding: 20px 22px; border: 1px solid var(--line); box-shadow: var(--shadow);
  opacity: 0; pointer-events: none; transition: opacity .5s ease, transform .5s ease;
}
.note-dt { background: var(--dt-soft); border-color: #f6d6b4; }
.note-hitl { background: var(--hitl-soft); border-color: #c6ddf3; }
.note-kicker {
  display: flex; align-items: center; gap: 8px; margin: 0 0 12px;
  font-size: 12.5px; font-weight: 700; text-transform: uppercase; letter-spacing: .08em;
}
.note-dt .note-kicker { color: #b9620f; }
.note-hitl .note-kicker { color: #1f68ad; }
.note-kicker .swatch { width: 22px; height: 0; border-top: 3px dashed currentColor; display: inline-block; }
.note-steps { list-style: none; counter-reset: st; margin: 0; padding: 0; display: grid; gap: 12px; }
.note-steps li {
  counter-increment: st; position: relative; padding-left: 32px;
  font-size: 14.5px; line-height: 1.45; color: var(--ink-2);
}
.note-steps li::before {
  content: counter(st); position: absolute; left: 0; top: 1px; width: 22px; height: 22px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center; font-size: 12px; font-weight: 700; color: #fff;
}
.note-dt .note-steps li::before { background: var(--dt); }
.note-hitl .note-steps li::before { background: var(--hitl); }
.note-steps b { display: block; color: var(--ink); font-size: 15px; font-weight: 650; }
.arch-hint {
  margin: 12px 0 0; text-align: center; color: var(--muted); font-size: 14px; transition: opacity .4s ease;
}
.arch-hint span { display: inline-block; animation: nudge 1.6s ease-in-out infinite; }
@keyframes nudge { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(4px); } }

/* Scroll-driven mode (enabled by main.js) */
/* main.js sets the scrolly height and --sticky-top so the pinned block is centered without extra blank space */
.scrolly.is-enabled .scrolly-sticky { position: sticky; top: var(--sticky-top, 63px); }
.scrolly .wrap.wide { max-width: 1360px; }
.scrolly.no-anim .arch-figure, .scrolly.no-anim .arch-note, .scrolly.no-anim .arch-ov, .scrolly.no-anim .arch-hint { transition: none !important; }
.scrolly:not(.is-enabled) .arch-note { display: none; }
.scrolly:not(.is-enabled) .arch-hint { display: none; }

@media (min-width: 901px) {
  .scrolly.is-enabled .arch-figure {
    width: var(--fw, 100%); margin: 0;
    transform: translateX(var(--tx-full, 0px)) scale(1); transform-origin: 0 50%;
    transition: transform .7s cubic-bezier(.2, .7, .2, 1);
  }
  .scrolly.is-enabled .arch-note {
    position: absolute; top: 50%; right: 0; width: var(--nw, 330px);
    transform: translate(18px, -50%);
  }
  .scrolly[data-step="1"] .arch-figure, .scrolly[data-step="2"] .arch-figure { transform: translateX(0) scale(var(--s-focus, .7)); }
  .scrolly[data-step="1"] .note-dt, .scrolly[data-step="2"] .note-hitl { transform: translate(0, -50%); }
}
@media (max-width: 900px) {
  .scrolly.is-enabled .arch-stage { display: grid; gap: 14px; }
  .scrolly.is-enabled .arch-figure { grid-area: 1 / 1; }
  .scrolly.is-enabled .arch-note { grid-area: 2 / 1; transform: translateY(10px); }
  .scrolly[data-step="1"] .note-dt, .scrolly[data-step="2"] .note-hitl { transform: none; }
}
.scrolly[data-step="1"] .ov-hitl, .scrolly[data-step="2"] .ov-dt { opacity: 1; }
.scrolly[data-step="1"] .note-dt, .scrolly[data-step="2"] .note-hitl { opacity: 1; pointer-events: auto; }
.scrolly:not([data-step="0"]) .arch-hint { opacity: 0; }

/* ---------- figures ---------- */
figure { margin: 0; }
figure img { border-radius: 10px; }
.zoomable a { display: block; cursor: zoom-in; }
.zoomable img { width: 100%; border: 1px solid var(--line); }

/* ---------- video ---------- */
.video-frame {
  position: relative; aspect-ratio: 16 / 9; width: 100%; max-width: 960px; margin: 0 auto;
  border-radius: var(--radius); overflow: hidden; background: #0d0f12 center / cover no-repeat; box-shadow: var(--shadow);
}
.video-frame iframe, .video-frame video { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
.video-placeholder {
  position: absolute; inset: 0; display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 10px;
  color: #fff; background: linear-gradient(180deg, rgba(10, 12, 16, .25), rgba(10, 12, 16, .55));
}
.video-placeholder svg { width: 68px; height: 68px; }
.video-placeholder p { margin: 0; font-weight: 600; letter-spacing: .01em; text-shadow: 0 1px 8px rgba(0, 0, 0, .5); }

/* ---------- twin viewer ---------- */
.twin-viewer {
  display: grid; grid-template-columns: 1fr 300px; gap: 0;
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow);
}
.twin-stage { position: relative; background: #1b1f24; aspect-ratio: 16 / 9; overflow: hidden; }
.twin-stage video {
  position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; display: block;
  transition: opacity .25s ease;
}
.twin-stage video.is-fading { opacity: .35; }
.twin-info { padding: 26px 24px; border-left: 1px solid var(--line); }
.twin-code { margin: 0; font-size: 13px; font-weight: 700; letter-spacing: .1em; color: var(--aged); }
.twin-info h3 { margin: 4px 0 10px; font-size: 21px; line-height: 1.3; }
.twin-info p { margin: 0; font-size: 15.5px; color: var(--ink-2); }
.twin-strip {
  grid-column: 1 / -1; display: grid; grid-template-columns: repeat(5, 1fr); gap: 10px;
  padding: 12px; border-top: 1px solid var(--line); background: var(--bg-soft);
}
.twin-thumb {
  position: relative; padding: 0; border: 2px solid transparent; border-radius: 9px; overflow: hidden; cursor: pointer;
  background: #1b1f24; aspect-ratio: 16 / 9; font: inherit;
}
.twin-thumb img { width: 100%; height: 100%; object-fit: cover; border-radius: 0; opacity: .78; transition: opacity .15s ease; }
.twin-thumb span {
  position: absolute; left: 6px; bottom: 6px; padding: 1px 7px; border-radius: 6px;
  font-size: 12px; font-weight: 700; letter-spacing: .05em; color: #fff; background: rgba(0, 0, 0, .55);
}
.twin-thumb:hover img { opacity: 1; }
.twin-thumb.is-active { border-color: var(--gold); }
.twin-thumb.is-active img { opacity: 1; }
.twin-thumb:focus-visible { outline: 3px solid var(--hitl); outline-offset: 2px; }

/* ---------- segmented control ---------- */
.seg { display: flex; justify-content: center; flex-wrap: wrap; gap: 6px; margin: 0 auto 16px; }
.seg-btn {
  font: inherit; font-size: 14.5px; font-weight: 600; cursor: pointer;
  padding: 8px 16px; border-radius: 999px; border: 1px solid var(--line); background: var(--card); color: var(--ink-2);
  transition: background .15s ease, color .15s ease, border-color .15s ease;
}
.seg-btn:hover { border-color: #cfd2d9; }
.seg-btn.is-active { background: var(--ink); border-color: var(--ink); color: #fff; }
.seg-btn:focus-visible { outline: 3px solid var(--hitl); outline-offset: 2px; }
.seg.small { margin: 0; justify-content: flex-end; }
.seg.small .seg-btn { padding: 6px 12px; font-size: 13.5px; }

/* ---------- compare slider ---------- */
.compare {
  --pos: 50%;
  position: relative; overflow: hidden; border-radius: var(--radius); box-shadow: var(--shadow);
  user-select: none; -webkit-user-select: none; touch-action: pan-y; background: #1b1f24;
}
.compare-img { width: 100%; height: auto; border-radius: 0; pointer-events: none; }
.compare-before { position: absolute; inset: 0; clip-path: inset(0 calc(100% - var(--pos)) 0 0); }
.compare-before .compare-img { width: 100%; height: 100%; object-fit: cover; }
.compare-handle {
  position: absolute; top: 0; bottom: 0; left: var(--pos); width: 0; pointer-events: none;
  border-left: 2px solid #fff; box-shadow: 0 0 0 1px rgba(0, 0, 0, .15);
}
.compare-handle .knob {
  position: absolute; top: 50%; left: -19px; width: 36px; height: 36px; margin-top: -18px; border-radius: 50%;
  background: #fff; box-shadow: 0 2px 10px rgba(0, 0, 0, .3);
}
.compare-handle .knob::before, .compare-handle .knob::after {
  content: ""; position: absolute; top: 50%; width: 0; height: 0; margin-top: -5px; border: 5px solid transparent;
}
.compare-handle .knob::before { left: 6px; border-right-color: var(--ink); }
.compare-handle .knob::after { right: 6px; border-left-color: var(--ink); }
/* ripple around the knob until the first drag */
.compare-handle .ripple {
  position: absolute; top: 50%; left: -19px; width: 36px; height: 36px; margin-top: -18px; border-radius: 50%;
  border: 2px solid rgba(255, 255, 255, .95); box-shadow: 0 0 6px rgba(0, 0, 0, .25);
  animation: ripple 2s cubic-bezier(.2, .6, .3, 1) infinite;
}
.compare-handle .ripple.r2 { animation-delay: 1s; }
@keyframes ripple { 0% { transform: scale(1); opacity: .95; } 100% { transform: scale(2.6); opacity: 0; } }
.compare.is-touched .ripple { display: none; }
.compare { cursor: ew-resize; }
.compare-range { /* keyboard access only; pointer dragging is handled in main.js */
  position: absolute; left: 0; bottom: 0; width: 100%; height: 1px; margin: 0; opacity: 0; pointer-events: none;
}
.compare:focus-within .compare-handle .knob { outline: 3px solid var(--hitl); }
.compare-label {
  position: absolute; top: 12px; padding: 3px 10px; border-radius: 6px; pointer-events: none;
  font-size: 13px; font-weight: 700; color: #fff; background: rgba(0, 0, 0, .55);
}
.compare-label.left { left: 12px; }
.compare-label.right { right: 12px; }

/* ---------- driver view ---------- */
.driver-view img { width: 100%; border-radius: var(--radius); box-shadow: var(--shadow); }

/* ---------- vehicles ---------- */
.vehicle-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
.vehicle {
  margin: 0; background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  overflow: hidden; box-shadow: var(--shadow);
}
.vehicle-media { position: relative; aspect-ratio: 16 / 9; background: #1b1f24; }
.vehicle-media video { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; display: block; }
.vehicle figcaption {
  margin: 0; padding: 10px 14px; display: flex; justify-content: space-between; align-items: baseline; gap: 10px;
  text-align: left; font-size: 15px; color: var(--ink);
}
.vehicle figcaption b { font-weight: 650; }
.vehicle figcaption span { color: var(--muted); font-size: 14px; }
.pair { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 12px 12px 4px; box-shadow: var(--shadow); }
.pair-imgs { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.pair-imgs > div { position: relative; }
.pair-imgs img { width: 100%; aspect-ratio: 2 / 1; object-fit: cover; border-radius: 8px; }
.tag {
  position: absolute; left: 8px; top: 8px; padding: 1px 8px; border-radius: 6px;
  font-size: 12px; font-weight: 700; color: #fff; background: rgba(0, 0, 0, .55);
}

/* ---------- case studies ---------- */
.case {
  margin-top: 28px; padding: 36px 36px 32px; border: 1px solid var(--line); border-radius: 16px;
  background: var(--card); box-shadow: var(--shadow);
}
.case + .case { margin-top: 36px; }
.case-head { max-width: 780px; margin: 0 auto 22px; text-align: center; }
.case-num { margin: 0; font-size: 12.5px; font-weight: 700; text-transform: uppercase; letter-spacing: .1em; color: var(--aged); }
.case-head h3 { margin: 6px 0 10px; font-size: clamp(21px, 2.4vw, 26px); line-height: 1.25; letter-spacing: -.01em; }
.case-head p { margin: 0; color: var(--ink-2); }

.facts {
  list-style: none; margin: 0 0 28px; padding: 0;
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px;
}
.facts li {
  padding: 12px 14px; border-radius: 10px; background: var(--bg-soft);
  font-size: 14px; line-height: 1.4; color: var(--ink-2);
}
.facts strong { display: block; font-size: 19px; color: var(--ink); letter-spacing: -.01em; margin-bottom: 2px; }

.fig-row { display: grid; grid-template-columns: 1.69fr 1fr; gap: 18px; align-items: start; margin-bottom: 28px; }
.fig-row img { width: 100%; border: 1px solid var(--line); }
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; align-items: start; margin-bottom: 28px; }
.split img { width: 100%; border: 1px solid var(--line); }
.split-text h4 { margin: 0 0 8px; font-size: 18px; }
.split-text p { margin: 0 0 12px; font-size: 15.5px; color: var(--ink-2); }
.equation {
  margin: 4px 0 14px !important; padding: 10px 14px; border-radius: 8px; background: var(--bg-soft);
  font-size: 18px !important; color: var(--ink) !important; text-align: center; font-family: "Cambria Math", "STIX Two Math", Georgia, serif;
}
.wide-fig { margin: 0 0 24px; }
.wide-fig img { width: 100%; border: 1px solid var(--line); background: #fff; }
.wide-fig .scroll-x a { display: block; cursor: zoom-in; }

/* PET explorer */
.explorer { border: 1px solid var(--line); border-radius: var(--radius); padding: 20px 20px 10px; background: #fcfcfb; }
.explorer-head { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: flex-start; gap: 12px; }
.explorer-head h4 { margin: 0 0 4px; font-size: 18px; }
.explorer-head .hint { text-align: left; margin: 0; }
.legend { display: flex; flex-wrap: wrap; align-items: center; gap: 6px 18px; margin: 14px 0 2px; font-size: 14px; color: var(--ink-2); }
.legend .key { display: inline-block; width: 12px; height: 12px; border-radius: 3px; margin-right: 6px; vertical-align: -1px; }
.key.rci { background: var(--rci); }
.key.std { background: var(--std); }
.legend-note { color: var(--muted); font-size: 13.5px; }
.chart svg { width: 100%; height: auto; display: block; overflow: visible; }
.chart .axis text, .chart .tick-label { fill: var(--muted); font-size: 12px; font-family: var(--font); }
.chart .grid line { stroke: #eceef2; }
.chart .bar-label { font-size: 11.5px; fill: var(--ink-2); font-family: var(--font); font-weight: 600; }
.chart .delta { font-size: 12.5px; font-weight: 700; font-family: var(--font); }
.chart .delta.good { fill: var(--good); }
.chart .delta.bad { fill: var(--warn); }
.chart rect.bar { transition: y .35s ease, height .35s ease; }

.findings { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; margin-top: 24px; }
.finding { padding: 16px 18px; border-radius: 10px; background: var(--bg-soft); border-left: 3px solid var(--good); }
.finding.warn { border-left-color: var(--warn); }
.finding p { margin: 0; font-size: 15px; line-height: 1.55; color: var(--ink-2); }
.finding .finding-k { font-size: 13px; font-weight: 700; color: var(--ink); margin-bottom: 6px; }

/* eco-driving modes */
.modes { margin: 0 0 28px; }
.modes-lead { margin: 0 auto 14px; max-width: 780px; text-align: center; color: var(--ink-2); font-size: 15.5px; }
.mode-list { list-style: none; counter-reset: mode; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.mode-list li {
  counter-increment: mode; position: relative; padding: 16px 18px 16px 18px; border-radius: 10px;
  background: var(--bg-soft); font-size: 14.5px; line-height: 1.5; color: var(--ink-2);
}
.mode-name { display: block; font-weight: 700; color: var(--ink); font-size: 15.5px; margin-bottom: 4px; }
.mode-name::before {
  content: counter(mode); display: inline-flex; align-items: center; justify-content: center;
  width: 22px; height: 22px; margin-right: 8px; border-radius: 50%; font-size: 12px; background: var(--ink); color: #fff;
  vertical-align: 1px;
}

/* metrics table */
.metrics { width: 100%; border-collapse: collapse; font-size: 14.5px; font-variant-numeric: tabular-nums; }
.metrics th, .metrics td { padding: 8px 6px; border-bottom: 1px solid var(--line); text-align: right; }
.metrics th { font-size: 12.5px; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); font-weight: 700; }
.metrics th:first-child, .metrics td:first-child { text-align: left; }
.metrics td:first-child { color: var(--ink); font-weight: 500; }
.metrics .col-red { width: 38%; text-align: left; }
.red-bar { display: flex; align-items: center; gap: 8px; width: 100%; }
.red-bar .track { flex: 1; height: 10px; border-radius: 3px; background: #e6efe9; overflow: hidden; }
.red-bar i { display: block; height: 100%; border-radius: 3px; background: var(--good); }
.red-bar b { font-weight: 700; color: var(--good); white-space: nowrap; }
.table-note { font-size: 13px !important; color: var(--muted) !important; margin: 8px 0 14px !important; }

/* ---------- citation ---------- */
.bibtex { position: relative; }
.bibtex pre {
  margin: 0; padding: 20px 22px; overflow-x: auto; border-radius: var(--radius);
  background: #1b1f24; color: #e9eaee; font: 13.5px/1.6 var(--mono);
}
.copy-btn {
  position: absolute; top: 10px; right: 10px; font: inherit; font-size: 13px; font-weight: 600; cursor: pointer;
  padding: 5px 12px; border-radius: 8px; border: 1px solid rgba(255, 255, 255, .2); background: rgba(255, 255, 255, .08); color: #fff;
}
.copy-btn:hover { background: rgba(255, 255, 255, .16); }
#citation p { color: var(--ink-2); }

/* ---------- footer ---------- */
.footer { padding: 28px 0 40px; text-align: center; color: var(--muted); font-size: 14px; border-top: 1px solid var(--line); }
.footer p { margin: 0; }

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  .cards.three, .findings, .mode-list { grid-template-columns: 1fr; }
  .facts { grid-template-columns: repeat(2, 1fr); }
  .twin-viewer { grid-template-columns: 1fr; }
  .twin-info { border-left: 0; border-top: 1px solid var(--line); }
  .split, .fig-row { grid-template-columns: 1fr; }
}
@media (max-width: 720px) {
  body { font-size: 16px; }
  .wrap { padding: 0 16px; }
  .topbar-inner { padding: 0 16px; gap: 12px; height: 56px; }
  .wordmark { font-size: 20px; }
  .lab-link { font-size: 14px; }
  .hero { padding: 40px 0 18px; }
  .authors { font-size: 16px; }
  .affils { font-size: 14px; flex-direction: column; }
  .section { padding: 52px 0; }
  .cards.two { grid-template-columns: 1fr; }
  .vehicle-grid { gap: 10px; }
  .vehicle figcaption { flex-direction: column; gap: 0; padding: 8px 10px; font-size: 14px; }
  .vehicle figcaption span { font-size: 13px; }
  .case { padding: 24px 16px 20px; border-radius: 12px; }
  .twin-strip { grid-template-columns: repeat(5, 1fr); gap: 6px; padding: 8px; }
  .twin-thumb span { font-size: 10px; left: 3px; bottom: 3px; padding: 0 4px; }
  .seg.small { justify-content: flex-start; }
  #overview .abstract { text-align: left; }
  .scroll-x { overflow-x: auto; -webkit-overflow-scrolling: touch; }
  .scroll-x img { min-width: 860px; }
  .explorer { padding: 16px 12px 6px; }
}

@media (prefers-reduced-motion: reduce) {
  .arch-figure, .arch-note, .arch-ov, .arch-hint { transition: none !important; }
  .arch-hint span, .compare-handle .ripple { animation: none; }
  .compare-handle .ripple { display: none; }
}