/* Palette taken from the explainer video (make_video.py) and the paper figures.
   Visual rules used everywhere:
   - .card: grey panel, 1px rule border. Used for every diagram, chart and example.
   - .finding: white, 1.5px navy border. One per research question.
   - green / red tints mean "uses the biological input" / "does not", as in the paper. */
:root {
  --navy: #1f2a44;
  --grey: #5b6275;
  --rule: #d5dae3;
  --panel: #f5f6f9;
  --model: #e8edf5;
  --bg: #ffffff;
  --green-bg: #e8f5ec;
  --green: #2e7d32;
  --red-bg: #fdecec;
  --red: #c62828;
  --dna: #d86ecc;
  --prot: #0f9ed5;
  --cell: #24a88f;
  --cell-l: #bfe6dd;
  --ribo: #c9ced8;
  --radius: 12px;
  --font: "Inter", "Helvetica Neue", Helvetica, Arial, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, Menlo, monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 64px; }
body {
  margin: 0; font-family: var(--font); color: var(--navy); background: var(--bg);
  line-height: 1.55; font-size: 16px; -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; display: block; }
a { color: var(--navy); }
sub { font-size: 0.7em; }
p { margin: 0 0 8px; }
p:last-child { margin-bottom: 0; }
.grey { color: var(--grey); }
.small { font-size: 14px; }
.g { color: var(--green); }
.r { color: var(--red); }

.wrap { max-width: 1100px; margin: 0 auto; padding: 0 16px; }
@media (min-width: 720px) { .wrap { padding: 0 32px; } }

/* ---------- top bar ---------- */
.topbar { position: sticky; top: 0; z-index: 50; background: rgba(255, 255, 255, 0.95); border-bottom: 1px solid var(--rule); }
.topbar-inner { max-width: 1100px; margin: 0 auto; padding: 10px 16px; display: flex; align-items: center; justify-content: space-between; gap: 16px; }
@media (min-width: 720px) { .topbar-inner { padding: 12px 32px; } }
.brand { font-weight: 700; font-size: 15px; text-decoration: none; white-space: nowrap; opacity: 0; visibility: hidden; transition: opacity 0.25s, visibility 0.25s; }
.topbar.scrolled .brand { opacity: 1; visibility: visible; }
.nav { display: flex; gap: 2px; overflow-x: auto; scrollbar-width: none; }
.nav::-webkit-scrollbar { display: none; }
.nav a { color: var(--grey); text-decoration: none; font-size: 14px; font-weight: 600; padding: 6px 10px; border-radius: 8px; white-space: nowrap; }
.nav a:hover { color: var(--navy); background: var(--panel); }
.nav a.is-current { color: var(--navy); background: var(--panel); }
@media (max-width: 1000px) { .brand { display: none; } .topbar-inner { justify-content: center; } }

/* ---------- hero ---------- */
.hero { padding: 48px 0 24px; }
.hero-grid { display: grid; gap: 36px; align-items: center; }
@media (min-width: 960px) { .hero-grid { grid-template-columns: 1.1fr 0.9fr; } }
h1 { font-size: clamp(30px, 4.6vw, 46px); line-height: 1.1; letter-spacing: -0.025em; font-weight: 800; margin: 0 0 18px; }
.authors { font-size: 17px; font-weight: 600; margin: 0 0 4px; }
.authors sup, .affils sup { font-size: 0.65em; color: var(--grey); }
.affils { color: var(--grey); font-size: 14px; margin: 0 0 16px; }
.logos { display: flex; align-items: center; gap: 22px; margin-bottom: 22px; flex-wrap: wrap; }
.logos img { height: 32px; width: auto; }
.logos .logo-mit { height: 24px; }
.actions { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 22px; }
.btn {
  display: inline-flex; align-items: center; padding: 8px 18px; border-radius: 8px; font: 600 15px var(--font);
  color: var(--navy); background: #fff; border: 1.5px solid var(--navy); text-decoration: none; cursor: pointer;
}
.btn:hover { background: var(--panel); }
.btn-dark { background: var(--navy); color: #fff; }
.btn-dark:hover { background: #2c3a5c; }
.lede { font-size: 17px; color: var(--grey); max-width: 560px; }
.video { margin: 0; }
.video video { width: 100%; aspect-ratio: 1 / 1; border-radius: var(--radius); border: 1px solid var(--rule); background: #fff; display: block; }
.video figcaption { color: var(--grey); font-size: 13px; padding-top: 8px; }

/* ---------- sections ---------- */
.section { padding: 56px 0; border-top: 1px solid var(--rule); }
.kicker { margin: 0 0 10px; font-weight: 600; color: var(--grey); font-size: 15px; display: flex; gap: 10px; align-items: baseline; flex-wrap: wrap; }
h2 { font-size: clamp(24px, 3.2vw, 32px); line-height: 1.2; letter-spacing: -0.02em; margin: 0 0 28px; font-weight: 800; max-width: 900px; }
h3 { font-size: 20px; margin: 0 0 6px; letter-spacing: -0.01em; }
.block-title { margin: 44px 0 14px; }
.sub { color: var(--grey); margin: -14px 0 18px; max-width: 860px; }
h3 + .sub { margin-top: 0; }
.subblock { margin: 0 0 44px; }
.note { color: var(--grey); font-size: 13.5px; margin: 12px 0 0; max-width: 900px; }
.rq-pill { display: inline-block; background: var(--navy); color: #fff; font-weight: 700; font-size: 12.5px; letter-spacing: 0.03em; padding: 2px 8px; border-radius: 6px; }
.closing { font-size: 17px; margin: 28px 0 0; max-width: 900px; }

/* ---------- shared components ---------- */
.card { background: var(--panel); border: 1px solid var(--rule); border-radius: var(--radius); padding: 16px 18px; margin-bottom: 14px; }
.card-title { font-weight: 700; margin-bottom: 6px; }
.grid-2 { display: grid; gap: 14px; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }
.grid-4 { display: grid; gap: 14px; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); }
.grid-2 > .card, .grid-4 > .card { margin-bottom: 0; }
.grid-2 + .card, .grid-2 + .grid-2, .card + .grid-2 { margin-top: 14px; }
.rq-card { text-decoration: none; display: block; }
.rq-card .card-title { margin-top: 10px; }
.rq-card:hover { border-color: var(--grey); }
.grid-4 .card .card-title { margin-top: 10px; }

.finding { background: #fff; border: 1.5px solid var(--navy); border-radius: var(--radius); padding: 16px 20px; max-width: 960px; }
.finding .finding-tag { font-size: 12px; font-weight: 700; letter-spacing: 0.06em; text-transform: uppercase; color: var(--grey); margin-bottom: 4px; }

.figure { margin: 28px 0 0; }
.figure img { width: 100%; border-radius: var(--radius); border: 1px solid var(--rule); }
.figure figcaption { color: var(--grey); font-size: 13.5px; margin-top: 8px; }

.legend { display: flex; flex-wrap: wrap; gap: 6px 18px; font-size: 13px; color: var(--grey); margin: 10px 0; }
.legend span { display: inline-flex; align-items: center; gap: 6px; }
.sw { display: inline-block; width: 13px; height: 13px; border: 1px solid var(--navy); border-radius: 2px; }
.sw-deg { background: var(--cell-l); }
.sw-ribo { background: var(--ribo); }
.line-sw { display: inline-block; width: 18px; height: 3px; border-radius: 2px; }

/* ---------- diagrams (inline SVG) ---------- */
.diagram { padding: 16px; margin-bottom: 0; }
.diagram svg { width: 100%; height: auto; display: block; font-family: var(--font); }
.diagram text { fill: var(--navy); }
.diagram .grey { fill: var(--grey); }
.t11 { font-size: 11px; } .t12 { font-size: 12px; } .t14 { font-size: 14px; } .t15 { font-size: 15px; } .t17 { font-size: 17px; } .t20 { font-size: 20px; }
.arrow { stroke: var(--navy); stroke-width: 1.6; }
.split { display: grid; gap: 18px; grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr); align-items: center; margin-bottom: 18px; }
@media (max-width: 860px) { .split { grid-template-columns: 1fr; } }
.split > .card { margin-bottom: 0; }
.split-even { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); }
@media (max-width: 860px) { .split-even { grid-template-columns: 1fr; } }
.diagram-wide svg { max-width: 820px; margin: 0 auto; }
.legend-block p { display: flex; align-items: center; gap: 10px; }
.swatch { width: 22px; height: 16px; border-radius: 3px; border: 1px solid; flex: none; }
.sw-uses { background: var(--green-bg); border-color: var(--green); }
.sw-nouse { background: var(--red-bg); border-color: var(--red); }

/* ---------- table ---------- */
.table-wrap { overflow-x: auto; }
table.models { width: 100%; border-collapse: collapse; font-size: 14.5px; min-width: 640px; }
.models th { text-align: left; font-weight: 700; color: var(--grey); font-size: 13px; padding: 8px 12px 8px 0; border-bottom: 1.5px solid var(--navy); }
.models td { padding: 10px 12px 10px 0; border-bottom: 1px solid var(--rule); vertical-align: top; }
.models td:first-child { font-weight: 700; white-space: nowrap; }
.c-dna { color: var(--dna); font-weight: 600; }
.c-prot { color: var(--prot); font-weight: 600; }
.c-cell { color: var(--cell); font-weight: 600; }

/* ---------- bar charts ---------- */
.chart-title { text-align: center; font-weight: 700; margin: 0; }
.chart-sub { text-align: center; font-size: 12.5px; color: var(--grey); margin: 0 0 24px; }
.plot { display: flex; align-items: flex-end; justify-content: center; gap: 14px; border-bottom: 1.5px solid var(--navy); position: relative; margin: 0 6px 0 34px; }
.plot .axis { position: absolute; left: -34px; top: 0; bottom: 0; width: 30px; font-size: 10.5px; color: var(--grey); }
.plot .axis span { position: absolute; right: 5px; transform: translateY(50%); }
.plot .axis::after { content: ""; position: absolute; right: 0; top: 0; bottom: 0; width: 1.5px; background: var(--navy); }
.group { display: flex; gap: 4px; align-items: flex-end; height: 100%; }
.bar { width: 44px; position: relative; border: 1.2px solid var(--navy); border-bottom: 0; height: 0; transition: height 0.9s cubic-bezier(0.2, 0.8, 0.2, 1); }
.bar .val { position: absolute; top: -18px; left: 50%; transform: translateX(-50%); font-size: 11.5px; font-weight: 600; font-variant-numeric: tabular-nums; white-space: nowrap; }
.xlabels { display: flex; justify-content: center; gap: 14px; margin: 5px 6px 0 34px; font-size: 12px; color: var(--grey); text-align: center; line-height: 1.25; }
.xlabels.groups { font-weight: 700; color: var(--navy); font-size: 13px; }
.ylab { font-size: 11px; color: var(--grey); margin: 0 0 18px; }
.hatch { background-image: repeating-linear-gradient(135deg, rgba(255, 255, 255, 0.75) 0 2px, transparent 2px 6px); }

.perturb-grid { display: grid; gap: 12px; grid-template-columns: repeat(3, minmax(0, 1fr)); }
@media (max-width: 860px) { .perturb-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
.pcard { border-radius: var(--radius); padding: 12px 10px 10px; border: 1px solid; }
.pcard.uses { background: var(--green-bg); border-color: #cbe6d2; }
.pcard.nouse { background: var(--red-bg); border-color: #f5cfcf; }
.pcard .mod-tag { display: block; text-align: center; font-weight: 700; font-size: 12px; letter-spacing: 0.04em; text-transform: uppercase; }
.pcard .chart-sub { margin-bottom: 4px; }
@media (max-width: 520px) {
  .perturb-grid { gap: 8px; }
  .pcard .plot, .pcard .xlabels { gap: 8px; margin-left: 28px; margin-right: 2px; }
  .pcard .plot .axis { left: -28px; }
  .pcard .bar { width: 36px; }
}
@media (max-width: 330px) { .perturb-grid { grid-template-columns: minmax(0, 1fr); } }

/* horizontal bars */
.hrow { display: grid; grid-template-columns: 170px minmax(0, 1fr) 150px; gap: 12px; align-items: center; margin: 10px 0; font-size: 14px; }
@media (max-width: 600px) { .hrow { grid-template-columns: 1fr; gap: 4px; } }
.hrow small { display: block; color: var(--grey); font-size: 12px; }
.htrack { height: 22px; background: #fff; border: 1px solid var(--rule); display: flex; overflow: hidden; border-radius: 3px; }
.htrack span { height: 100%; width: 0; transition: width 1s cubic-bezier(0.2, 0.8, 0.2, 1); }
.hrow .num { font-weight: 600; font-variant-numeric: tabular-nums; }
.hrow .num small { font-weight: 400; }

.probe-wrap { display: grid; gap: 18px; grid-template-columns: 220px minmax(0, 1fr); align-items: center; }
@media (max-width: 760px) { .probe-wrap { grid-template-columns: 1fr; } .probe-diagram { max-width: 240px; margin: 0 auto; } }
.probe-wrap .bar { width: 38px; }
.probe-wrap .plot, .probe-wrap .xlabels { gap: 10px; }
.probe-wrap .xlabels span { width: 38px; font-size: 10.5px; }

/* ---------- gene chips + C2S line plots ---------- */
.mini-title { font-weight: 700; margin: 0 0 8px; font-size: 15px; }
.mini-title span { font-weight: 400; font-size: 13px; margin-left: 6px; }
.chips { display: flex; flex-wrap: wrap; gap: 4px; margin-bottom: 12px; }
.chip { font: 500 12.5px var(--mono); padding: 1px 6px; border: 1px solid var(--navy); border-radius: 4px; background: #fff; transition: opacity 0.3s; }
.chip.deg { background: var(--cell-l); }
.chip.ribo { background: var(--ribo); }
.chip.gone { opacity: 0.2; text-decoration: line-through; }
.slider-row { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; font-size: 14px; margin: 4px 0; }
.slider-row input { flex: 1; min-width: 180px; accent-color: var(--cell); }
.lineplot { background: #fff; border: 1px solid var(--rule); border-radius: 10px; padding: 10px; }
.lineplot svg { width: 100%; height: auto; display: block; font-family: var(--font); }
.lineplot text { fill: var(--navy); }
.lineplot .tick { font-size: 10px; fill: var(--grey); }
.lineplot .pt { transition: r 0.2s; }

.seq { font-family: var(--mono); font-size: 14px; }
.mono-list { font-family: var(--mono); font-size: 13px; line-height: 1.7; }

.bib { position: relative; overflow-x: auto; }
.bib pre { margin: 0; font: 13.5px/1.6 var(--mono); }
.copy-btn { position: absolute; right: 12px; top: 12px; padding: 4px 12px; font-size: 13px; }

.takeaways { grid-template-columns: repeat(2, minmax(0, 1fr)); }
@media (max-width: 700px) { .takeaways { grid-template-columns: 1fr; } }
.takeaways img { width: 100%; margin-top: 12px; }
.takeaways .card-title { margin-top: 10px; }
.footer { border-top: 1px solid var(--rule); padding: 24px 0 36px; font-size: 14px; color: var(--grey); }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .bar, .htrack span, .chip { transition: none !important; }
}