/* Adaptive Tutor — "Ledger"
   ────────────────────────────────────────────────────────────────────────────
   CONVICTION: every claim on this page ships with the instrument that proves it.

   Reference: attio.com, torn down over three Chromium passes on 2026-07-31.
   What that teardown actually measured, and what it changed here:
     · No GSAP, no Lenis, no WebGL, no video, no horizontal scroll. Motion is
       CSS/DOM only — 198 moving elements, max translateY 202px, max scale delta
       0.058. Scale is essentially unused. So reveals here travel 24-40px and
       never scale. The previous three builds crossed 120px; that difference IS
       the word "sober".
     · Hover state on every button and link changed COLOUR and nothing else.
       No lift, no shadow-pop, no transform. Copied exactly.
     · Body weight 500, not 400. Negative tracking on everything, at every size.
     · Ground defined in lab(), never #FFF. Ink never #000.
     · One accent, used sparingly (17 occurrences on a 17,668px page).

   IP rule: structure and principles only. No copied text, asset, colour or mark.
   ──────────────────────────────────────────────────────────────────────────── */

/* ── faces ─────────────────────────────────────────────────────────
   G1: self-hosted, zero CDN, and both sans are VARIABLE cut to a non-default
   instance (Instrument Sans 580 display, Inter 450 body). A variable font
   parked on 400/700 is the template signal the gate exists to catch. */
@font-face{font-family:'Instrument Sans';src:url('./vendor/fonts/instrument-sans-latin-wght-normal.woff2') format('woff2-variations');
  font-weight:100 900;font-display:swap;font-style:normal}
@font-face{font-family:'Inter';src:url('./vendor/fonts/inter-latin-wght-normal.woff2') format('woff2-variations');
  font-weight:100 900;font-display:swap;font-style:normal}
@font-face{font-family:'IBM Plex Mono';src:url('./vendor/fonts/ibm-plex-mono-latin-400-normal.woff2') format('woff2');
  font-weight:400;font-display:swap;font-style:normal}

:root{
  /* G3 — no pure white, no pure black. oklch so the neutrals carry a consistent
     cool cast instead of drifting hue as they lighten. */
  --paper:    oklch(99.1% 0.003 250);
  --paper-2:  oklch(97.4% 0.004 250);
  --paper-3:  oklch(95.2% 0.005 250);
  --slate:    oklch(21.5% 0.015 265);   /* ink            — 15.9:1 on paper */
  --slate-2:  oklch(50.0% 0.020 265);   /* two-tone grey  —  7.4:1 */
  /* 52%, not the 57% first chosen: measured against the tint grounds the mono labels
     actually sit on, 57% returned 4.17-4.37:1 — under AA for text this small. */
  --slate-3:  oklch(52.0% 0.017 265);   /* labels, mono */
  --line:     oklch(90.5% 0.006 265);
  --line-2:   oklch(84.0% 0.008 265);

  /* ONE accent family. Indigo because it is the colour this product plots in:
     the mastery posterior is a probability curve, and the curve is the accent.
     272deg is clear of the firm's teal (174), crimson (353) and orange (30). */
  --indigo:   oklch(48.5% 0.200 272);   /* 7.1:1 on paper — text-capable */
  --indigo-2: oklch(93.5% 0.038 272);   /* pill / tint ground */
  --indigo-3: oklch(70.0% 0.150 272);   /* plot strokes on tint */
  /* signal, not accent: reserved for the gate refusing. */
  --amber:    oklch(52.0% 0.150 55);

  --display:'Instrument Sans',system-ui,sans-serif;
  --body:'Inter',system-ui,sans-serif;
  --mono:'IBM Plex Mono',ui-monospace,monospace;

  /* G2 — commit high. Attio's own h1 is 64px, which sits in the banned 40-64
     middle zone; we take the ambition end instead. */
  --t-hero:clamp(3.4rem,7.6vw,8.5rem);
  /* Section heads carry the two-tone device (claim in ink + mechanism in grey) as ONE
     sentence, so they run long. At the first size tried (3.9rem/62px) a 25-word head
     stacked eight lines deep and swallowed the section. The reference sets its
     equivalent at 40px over a wide measure; this is that, with our ambition kept for
     the h1 where a short declaration can carry it. */
  --t-1:clamp(1.85rem,1.35rem + 1.72vw,2.8rem);
  --t-2:clamp(1.55rem,1.2rem + 1.3vw,2.3rem);
  --t-3:clamp(1.18rem,1.06rem + .42vw,1.45rem);
  --t-body:clamp(1.06rem,1rem + .28vw,1.22rem);   /* G2: 18-24px, never 16 */
  --t-mono:.74rem;

  --gut:clamp(1.15rem,4.6vw,5rem);
  --stack:clamp(4.5rem,9.5vh,8.5rem);
  --measure:37rem;
  --radius:10px;
  --radius-lg:16px;
  --ease:cubic-bezier(.22,.61,.24,1);
}

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

body{
  margin:0;background:var(--paper);color:var(--slate);
  font-family:var(--body);font-variation-settings:'wght' 450;
  font-size:var(--t-body);line-height:1.62;letter-spacing:-.011em;
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;
  /* clip, not hidden: overflow-x:hidden forces overflow-y to auto, which makes
     <body> a scroll container and silently kills every position:sticky
     descendant — and the step rail below is sticky. */
  overflow-x:clip;
}
img,svg{max-width:100%;display:block}

/* G4 — texture derived from the subject: squared exercise paper. Two SVG-free
   gradient grids, 1px lines at ~4% ink, so it costs nothing and never reads as
   a "pattern". This is the page's ground rule, literally. */
.grid-ground{
  background-image:
    linear-gradient(to right, oklch(21.5% .015 265/.045) 1px, transparent 1px),
    linear-gradient(to bottom, oklch(21.5% .015 265/.045) 1px, transparent 1px);
  background-size:26px 26px;
}
.dot-ground{
  background-image:radial-gradient(oklch(21.5% .015 265/.09) 1px, transparent 1px);
  background-size:22px 22px;
}

/* ── type ──────────────────────────────────────────────────────────
   Tracking tightens as size grows, the way the reference does it at every
   step (-0.16px at 16px through -1.28px at 64px). */
h1,h2,h3,h4{font-family:var(--display);margin:0;color:var(--slate);text-wrap:balance}
h1{font-variation-settings:'wght' 580;font-size:var(--t-hero);
   line-height:.93;letter-spacing:-.038em;max-width:15ch}
h2{font-variation-settings:'wght' 570;font-size:var(--t-1);
   line-height:1.1;letter-spacing:-.028em;max-width:27ch}
h3{font-variation-settings:'wght' 560;font-size:var(--t-2);
   line-height:1.12;letter-spacing:-.024em}
h4{font-variation-settings:'wght' 560;font-size:var(--t-3);
   line-height:1.24;letter-spacing:-.018em}
p{margin:0 0 1.15rem;max-width:var(--measure)}
p:last-child{margin-bottom:0}
b,strong{font-variation-settings:'wght' 600;color:var(--slate)}
em{font-style:italic}
a{color:inherit}
code{font-family:var(--mono);font-size:.86em;background:var(--paper-3);
  padding:.1em .34em;border-radius:4px;letter-spacing:0}

/* THE SIGNATURE SENTENCE FORM — claim in ink, mechanism in grey, one sentence.
   Lifted as a *device* from the reference, written fresh.
   The reference keeps both halves at one size because its claims are four words long.
   Ours run to a full clause, and at parity the grey half swallowed the section, so the
   mechanism steps down one notch inside headings only. Body-level two-tone stays at
   parity, where the reference's proportions hold. */
.said{color:var(--slate)}
.means{color:var(--slate-2)}
h2 .means,h3 .means{font-size:.84em;font-variation-settings:'wght' 480;letter-spacing:-.022em}

/* Structural paragraphs are chrome, not prose: the global measure is for reading
   columns and was clamping instrument footers to 592px inside 1116px cards. */
.inst-foot,.gate-rule,.gate-verdict,.hero-note,.inst-body > .mono--data{max-width:none}

/* fixed header — anchor targets have to clear it or every in-page link lands
   with its heading tucked under the bar */
:target,section[id],article[id]{scroll-margin-top:calc(56px + 1.5rem)}

.mono{font-family:var(--mono);font-size:var(--t-mono);letter-spacing:.075em;
  text-transform:uppercase;color:var(--slate-3);line-height:1.5}
.mono--data{text-transform:none;letter-spacing:.01em;font-size:.82rem;color:var(--slate)}

.lede{font-size:clamp(1.16rem,1.02rem + .55vw,1.42rem);line-height:1.5;
  color:var(--slate-2);letter-spacing:-.016em;max-width:34rem}

.sr-only{position:absolute!important;width:1px!important;height:1px!important;
  padding:0!important;margin:-1px!important;overflow:hidden;
  clip-path:inset(50%);white-space:nowrap;border:0}

/* ── layout ────────────────────────────────────────────────────────*/
.wrap{width:100%;max-width:78rem;margin-inline:auto;padding-inline:var(--gut)}
.wrap--narrow{max-width:62rem}
section{padding-block:var(--stack)}
.band{border-top:1px solid var(--line)}
.band--tint{background:var(--paper-2)}
.eyebrow{display:inline-flex;align-items:center;gap:.5rem;margin:0 0 1.5rem;
  padding:.3rem .68rem;border-radius:999px;background:var(--indigo-2);
  color:var(--indigo);font-family:var(--mono);font-size:.68rem;
  letter-spacing:.09em;text-transform:uppercase}
.eyebrow::before{content:'';width:5px;height:5px;border-radius:50%;background:currentColor}

/* ── nav — G10, a designed object, not a header bar ────────────────
   A hairline rail carrying a live mono section readout on the left of the
   wordmark. The nav tells you where you are in the argument; that is the
   instructive brief applied to chrome. */
.topbar{position:fixed;inset:0 0 auto;z-index:60;background:oklch(99.1% .003 250/.82);
  backdrop-filter:blur(14px);border-bottom:1px solid var(--line)}
.topbar-in{display:flex;align-items:center;gap:1.4rem;height:56px}
.brand{display:flex;align-items:center;gap:.55rem;font-family:var(--display);
  font-variation-settings:'wght' 600;font-size:1.02rem;letter-spacing:-.028em;
  text-decoration:none;flex:0 0 auto}
.brand-mark{width:19px;height:19px;flex:0 0 auto}
.bm-bg{fill:var(--indigo-2)}
.bm-curve{fill:none;stroke:var(--indigo)}
.nav-here{flex:1 1 auto;min-width:0;display:flex;align-items:center;gap:.5rem;
  font-family:var(--mono);font-size:.68rem;letter-spacing:.09em;
  text-transform:uppercase;color:var(--slate-3);
  white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.nav-here i{width:14px;height:1px;background:var(--line-2);flex:0 0 auto}
.nav-here b{font-variation-settings:'wght' 400;color:var(--slate);font-weight:400}
.nav-links{display:flex;align-items:center;gap:.2rem}
/* :not(.btn) matters — `.nav-links a` (0,1,1) outranks `.btn` (0,1,0), so without it
   the nav's primary CTA silently lost its pill and rendered as a 7px rounded rect
   while the identical button in the hero stayed a pill. */
.nav-links a:not(.btn){font-size:.9rem;letter-spacing:-.012em;text-decoration:none;
  color:var(--slate-2);padding:.42rem .62rem;border-radius:7px;
  transition:color .18s var(--ease),background-color .18s var(--ease)}
.nav-links a:not(.btn):hover{color:var(--slate);background:var(--paper-3)}

/* #8 scroll progress — page-level orientation cue */
#progress{position:fixed;top:0;left:0;right:0;height:2px;z-index:70;
  pointer-events:none;transform:scaleX(var(--sp,0));transform-origin:0 50%;
  background:var(--indigo)}
@keyframes sp-grow{from{transform:scaleX(0)}to{transform:scaleX(1)}}
@supports (animation-timeline:scroll(root)){
  #progress{animation:sp-grow linear both;animation-timeline:scroll(root)}
}

/* ── buttons — G10. Colour-only state change, exactly as measured on the
   reference: no lift, no shadow pop, no transform anywhere. ─────────*/
.btn{display:inline-flex;align-items:center;justify-content:center;gap:.5rem;
  font-family:var(--body);font-variation-settings:'wght' 520;
  font-size:.95rem;letter-spacing:-.014em;line-height:1;
  padding:.72rem 1.15rem;border-radius:999px;border:1px solid transparent;
  text-decoration:none;cursor:pointer;background:transparent;color:var(--slate);
  -webkit-appearance:none;appearance:none;
  transition:background-color .18s var(--ease),color .18s var(--ease),
             border-color .18s var(--ease)}
.btn--primary{background:var(--slate);color:var(--paper)}
.btn--primary:hover{background:oklch(30% .018 265)}
.btn--ghost{border-color:var(--line-2);color:var(--slate)}
.btn--ghost:hover{background:var(--paper-3);border-color:var(--slate-3)}
.btn--sm{font-size:.82rem;padding:.5rem .82rem}
.btn--lg{font-size:1.02rem;padding:.9rem 1.5rem}
.btn kbd{font-family:var(--mono);font-size:.68rem;letter-spacing:.04em;
  opacity:.6;border:0;background:none;padding:0}
:where(a,button,summary,[tabindex]):focus-visible{
  outline:2px solid var(--indigo);outline-offset:2px;border-radius:6px}

/* ── hero — G5 archetype 1: the declaration IS the hero ────────────*/
.hero{padding-top:calc(56px + var(--stack));padding-bottom:0}
.hero h1{margin-bottom:1.6rem}
.hero .lede{margin-bottom:2rem}
.hero-actions{display:flex;flex-wrap:wrap;gap:.6rem;margin-bottom:3.4rem}
.hero-note{display:flex;flex-wrap:wrap;gap:.55rem 1.5rem;margin-top:1.4rem}
.hero-note span{display:inline-flex;align-items:center;gap:.45rem}
.hero-note span::before{content:'';width:4px;height:4px;border-radius:50%;
  background:var(--indigo);flex:0 0 auto}

/* ── THE INSTRUMENT — the signature element ────────────────────────
   Every claim on this page is followed by one of these: a mono label bar, a
   readable body (plot, table, readout), and a footer citing the exact file in
   the repository that implements it. The conviction, made physical. */
.inst{border:1px solid var(--line);border-radius:var(--radius-lg);
  background:var(--paper);overflow:hidden}
.inst-head{display:flex;align-items:center;justify-content:space-between;
  gap:1rem;padding:.72rem 1.05rem;border-bottom:1px solid var(--line);
  background:var(--paper-2)}
.inst-head h3,.inst-head h4{font-family:var(--mono);font-size:.7rem;
  letter-spacing:.09em;text-transform:uppercase;color:var(--slate-3);
  font-variation-settings:'wght' 400;margin:0}
.inst-tag{font-family:var(--mono);font-size:.66rem;letter-spacing:.06em;
  padding:.16rem .48rem;border-radius:999px;background:var(--indigo-2);
  color:var(--indigo);white-space:nowrap}
.inst-body{padding:1.35rem 1.05rem}
.inst-foot{padding:.62rem 1.05rem;border-top:1px solid var(--line);
  background:var(--paper-2);font-family:var(--mono);font-size:.66rem;
  letter-spacing:.045em;color:var(--slate-3);
  overflow-x:auto;white-space:nowrap;scrollbar-width:thin}

/* ── figures ───────────────────────────────────────────────────────*/
figure.plate{margin:0;border-radius:var(--radius-lg);overflow:clip;
  border:1px solid var(--line);background:var(--paper-2)}
figure.plate img{width:100%;height:auto;aspect-ratio:16/9;object-fit:cover}
figure.plate figcaption{padding:.85rem 1.05rem;border-top:1px solid var(--line);
  font-family:var(--mono);font-size:.7rem;letter-spacing:.03em;
  text-transform:none;color:var(--slate-3)}
figure.plate figcaption b{color:var(--slate);font-variation-settings:'wght' 500;
  display:block;font-size:.66rem;letter-spacing:.09em;text-transform:uppercase;
  margin-bottom:.3rem}

/* ── two-column instructive rows ───────────────────────────────────*/
.row{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1.08fr);
  gap:clamp(2rem,5vw,4.5rem);align-items:start}
.row--flip > *:first-child{order:2}
/* minmax(0,1fr), never a bare 1fr: `1fr` means `minmax(auto,1fr)`, whose auto floor is
   max-content, so one nowrap child (the code footers, the literature table) drags the
   whole column past the viewport. Measured at 375px: the document was 585px wide. */
@media (max-width:900px){.row{grid-template-columns:minmax(0,1fr);gap:2.4rem}
  .row--flip > *:first-child{order:0}}

/* ── the step rail — the reference's pinned index, rebuilt ─────────
   #4 sticky pin + active tracking. The rail is the table of contents for a
   single turn, and it says which of the five you are looking at. */
.rail-wrap{display:grid;grid-template-columns:15.5rem minmax(0,1fr);
  gap:clamp(2rem,4vw,4rem);align-items:start}
.rail{position:sticky;top:calc(56px + 2rem);align-self:start}
.rail ol{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:.1rem}
.rail button{display:flex;align-items:baseline;gap:.65rem;width:100%;
  text-align:left;background:none;border:0;cursor:pointer;
  padding:.5rem .3rem .5rem .85rem;border-left:2px solid transparent;
  font-family:var(--body);font-size:1rem;letter-spacing:-.016em;
  font-variation-settings:'wght' 480;color:var(--slate-3);
  transition:color .2s var(--ease),border-color .2s var(--ease)}
.rail button:hover{color:var(--slate-2)}
.rail li[aria-current="true"] button{color:var(--slate);
  border-left-color:var(--indigo);font-variation-settings:'wght' 560}
.rail .n{font-family:var(--mono);font-size:.66rem;letter-spacing:.06em;
  color:var(--slate-3);flex:0 0 auto}
.rail li[aria-current="true"] .n{color:var(--indigo)}
@media (max-width:900px){
  .rail-wrap{grid-template-columns:minmax(0,1fr)}
  .rail{position:static;margin-bottom:1.6rem;overflow-x:auto;
    scrollbar-width:none;-webkit-overflow-scrolling:touch}
  .rail ol{flex-direction:row;gap:.35rem;min-width:max-content;padding-bottom:.3rem}
  .rail button{border-left:0;border-bottom:2px solid transparent;white-space:nowrap;
    padding:.4rem .2rem .5rem}
  .rail li[aria-current="true"] button{border-left-color:transparent;
    border-bottom-color:var(--indigo)}
}
.turn{border-top:1px solid var(--line);padding:1.6rem 0}
.turn:first-child{border-top:0;padding-top:0}
.turn h4{margin-bottom:.5rem}
.turn p{margin-bottom:.7rem}
.turn .foot{font-family:var(--mono);font-size:.66rem;letter-spacing:.045em;
  color:var(--slate-3);margin:0}

/* ── lists that teach ──────────────────────────────────────────────*/
.speclist{list-style:none;margin:0 0 1.4rem;padding:0;display:flex;
  flex-direction:column;gap:.1rem}
.speclist li{display:grid;grid-template-columns:2.5rem minmax(0,1fr);
  gap:.9rem;align-items:start;padding:.82rem 0;border-top:1px solid var(--line)}
.speclist li:first-child{border-top:0}
.speclist .k{font-family:var(--mono);font-size:.95rem;color:var(--indigo);
  letter-spacing:.01em;line-height:1.5}
.speclist p{margin:0;font-size:.99rem;color:var(--slate-2)}
.speclist b{color:var(--slate)}

.steps{list-style:none;counter-reset:s;margin:0;padding:0;
  display:flex;flex-direction:column}
.steps li{counter-increment:s;display:grid;
  grid-template-columns:1.9rem minmax(0,1fr);gap:.9rem;
  padding:.95rem 0;border-top:1px solid var(--line);font-size:.99rem;
  color:var(--slate-2)}
.steps li:first-child{border-top:0}
.steps li::before{content:counter(s,decimal-leading-zero);
  font-family:var(--mono);font-size:.7rem;letter-spacing:.06em;
  color:var(--slate-3);padding-top:.28rem}
.steps b{color:var(--slate)}

/* ── stat row — G2 numerals, mono, with the accent rule ────────────*/
.stats{display:grid;grid-template-columns:repeat(auto-fit,minmax(9.5rem,1fr));
  gap:1.6rem 1.2rem;margin:0;padding:0;list-style:none}
.stats div{border-left:2px solid var(--indigo);padding-left:.85rem}
.stats dt{font-family:var(--display);font-variation-settings:'wght' 560;
  font-size:clamp(1.8rem,1.3rem + 1.7vw,2.6rem);letter-spacing:-.035em;
  line-height:1;color:var(--slate);font-feature-settings:'tnum' 1}
.stats dd{margin:.4rem 0 0;font-family:var(--mono);font-size:.68rem;
  letter-spacing:.075em;text-transform:uppercase;color:var(--slate-3)}

/* ── the mastery instrument (hero plot) ────────────────────────────*/
.plot{width:100%;height:auto;display:block}
.plot .axis{stroke:var(--line-2);stroke-width:1}
.plot .grid{stroke:var(--line);stroke-width:1}
.plot .thresh{stroke:var(--slate-3);stroke-width:1;stroke-dasharray:3 3}
.plot .curve{fill:none;stroke:var(--indigo);stroke-width:2.5;
  stroke-linecap:round;stroke-linejoin:round}
.plot .band{fill:var(--indigo);opacity:.07}
.plot text{font-family:var(--mono);font-size:9px;letter-spacing:.06em;
  fill:var(--slate-3)}
.plot .dot{fill:var(--paper);stroke:var(--indigo);stroke-width:2}
.plot .dot--pass{fill:var(--indigo)}

/* ── knowledge graph instrument ────────────────────────────────────*/
.kgraph{width:100%;height:auto}
.kgraph .edge{stroke:var(--line-2);stroke-width:1}
.kgraph .node{fill:var(--indigo-2);stroke:var(--indigo-3);stroke-width:1}
.kgraph .node--on{fill:var(--indigo);stroke:var(--indigo)}

/* ── the gate — the interactive centrepiece ────────────────────────*/
.gate-read{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));
  gap:.8rem;margin:0 0 1.1rem}
.gate-read > div{border:1px solid var(--line);border-radius:var(--radius);
  padding:.7rem .8rem;background:var(--paper-2)}
.gate-read dt{font-family:var(--mono);font-size:.63rem;letter-spacing:.085em;
  text-transform:uppercase;color:var(--slate-3);margin-bottom:.3rem}
.gate-read dd{margin:0;font-family:var(--mono);font-size:1.24rem;
  letter-spacing:-.01em;color:var(--slate);font-feature-settings:'tnum' 1}
.gate-read dd.ok{color:var(--indigo)}
.gate-verdict{display:flex;align-items:flex-start;gap:.55rem;margin:0 0 1.1rem;
  padding:.72rem .85rem;border-radius:var(--radius);
  border:1px solid var(--line);background:var(--paper-2);
  font-family:var(--mono);font-size:.78rem;letter-spacing:.01em;
  text-transform:none;color:var(--slate-2);line-height:1.5}
.gate-verdict::before{content:'';width:7px;height:7px;border-radius:50%;
  margin-top:.42rem;flex:0 0 auto;background:var(--slate-3)}
.gate[data-state="refused"] .gate-verdict{border-color:oklch(52% .15 55/.4);
  background:oklch(52% .15 55/.06);color:var(--amber)}
.gate[data-state="refused"] .gate-verdict::before{background:var(--amber)}
.gate[data-state="pass"] .gate-verdict{border-color:oklch(48.5% .2 272/.4);
  background:var(--indigo-2);color:var(--indigo)}
.gate[data-state="pass"] .gate-verdict::before{background:var(--indigo)}
.gate-actions{display:flex;flex-wrap:wrap;gap:.5rem}
.gate-rule{font-family:var(--mono);font-size:.7rem;letter-spacing:.03em;
  text-transform:none;color:var(--slate-3);margin:0 0 1rem;
  padding:.6rem .75rem;border-radius:var(--radius);background:var(--paper-3);
  overflow-x:auto;white-space:nowrap;scrollbar-width:thin}
@media (max-width:560px){.gate-read{grid-template-columns:1fr}}

/* ── the sigma collapse ────────────────────────────────────────────*/
.sigma-stage{display:flex;flex-wrap:wrap;align-items:baseline;gap:.5rem .9rem;
  margin-top:1.1rem;opacity:0;max-height:0;overflow:hidden;
  transition:opacity .5s var(--ease),max-height .5s var(--ease)}
:root[data-claim="advertised"] .sigma-stage{opacity:1;max-height:12rem}
.sigma-big{font-family:var(--display);font-variation-settings:'wght' 560;
  font-size:clamp(2.2rem,1.6rem + 2vw,3.2rem);letter-spacing:-.04em;
  color:var(--slate-3);text-decoration:line-through;
  text-decoration-thickness:2px;text-decoration-color:var(--amber)}
.sigma-arrow{font-family:var(--mono);font-size:.68rem;letter-spacing:.09em;
  text-transform:uppercase;color:var(--slate-3)}
.sigma-real{font-family:var(--display);font-variation-settings:'wght' 560;
  font-size:clamp(2.2rem,1.6rem + 2vw,3.2rem);letter-spacing:-.04em;
  color:var(--indigo)}

/* ── literature table ──────────────────────────────────────────────*/
.lit-wrap{overflow-x:auto;scrollbar-width:thin}
table.lit{width:100%;border-collapse:collapse;font-size:.95rem;min-width:34rem}
table.lit th{text-align:left;font-family:var(--mono);font-size:.64rem;
  letter-spacing:.09em;text-transform:uppercase;color:var(--slate-3);
  font-weight:400;padding:0 1rem .6rem 0;border-bottom:1px solid var(--line-2)}
table.lit td{padding:.85rem 1rem .85rem 0;border-bottom:1px solid var(--line);
  vertical-align:top;color:var(--slate-2)}
table.lit td:first-child{color:var(--slate)}
table.lit .eff{font-family:var(--mono);font-size:1rem;color:var(--indigo);
  letter-spacing:-.01em;display:block}
table.lit small{display:block;margin-top:.2rem;font-size:.78rem;color:var(--slate-3)}

/* ── the 60-skill index ────────────────────────────────────────────*/
details.kc{border:1px solid var(--line);border-radius:var(--radius-lg);
  background:var(--paper);overflow:hidden}
details.kc > summary{cursor:pointer;list-style:none;padding:.95rem 1.05rem;
  display:flex;align-items:center;justify-content:space-between;gap:1rem;
  font-family:var(--mono);font-size:.7rem;letter-spacing:.085em;
  text-transform:uppercase;color:var(--slate-2);background:var(--paper-2)}
details.kc > summary::-webkit-details-marker{display:none}
details.kc > summary::after{content:'+';font-size:1rem;color:var(--slate-3)}
details.kc[open] > summary::after{content:'\2212'}
details.kc > summary:hover{color:var(--slate)}
.kc-body{padding:1.35rem 1.05rem}
.kc-band{display:flex;align-items:center;gap:.55rem;margin:1.6rem 0 .7rem;
  font-family:var(--mono);font-size:.66rem;letter-spacing:.09em;
  text-transform:uppercase;color:var(--slate-3);font-variation-settings:'wght' 400}
.kc-band:first-of-type{margin-top:0}
.kc-band i{width:7px;height:7px;border-radius:2px;background:var(--indigo);
  flex:0 0 auto;font-style:normal}
.kc-band i.b{background:var(--indigo-3)}
.kc-band i.c{background:var(--line-2)}
.kc-list{columns:2;column-gap:2.2rem;list-style:none;margin:0;padding:0;
  font-size:.9rem;color:var(--slate-2)}
.kc-list li{break-inside:avoid;padding:.3rem 0;border-bottom:1px solid var(--line)}
.kc-list .std{display:block;font-family:var(--mono);font-size:.62rem;
  letter-spacing:.05em;color:var(--slate-3);margin-top:.1rem}
@media (max-width:760px){.kc-list{columns:1}}

/* ── pricing ───────────────────────────────────────────────────────*/
.price{display:flex;align-items:baseline;gap:.6rem;margin-bottom:.5rem}
.price-n{font-family:var(--display);font-variation-settings:'wght' 570;
  font-size:clamp(2.6rem,2rem + 2.6vw,4rem);letter-spacing:-.042em;
  line-height:1;margin:0;color:var(--slate)}
.price-n span{font-family:var(--body);font-size:1rem;color:var(--slate-3);
  font-variation-settings:'wght' 450;letter-spacing:-.01em}

/* ── footer ────────────────────────────────────────────────────────*/
footer{border-top:1px solid var(--line);background:var(--paper-2);
  padding-block:var(--stack) 3rem}
footer p{font-size:.88rem;color:var(--slate-2);max-width:46rem;margin-bottom:.9rem}
footer .mono{margin-bottom:1.4rem}
.nowrap{white-space:nowrap}

/* ══ MOTION ════════════════════════════════════════════════════════
   Amplitude is set by measurement, not taste. The reference's largest scroll
   translate was 202px and its largest scale delta was 0.058 — i.e. it does not
   scale anything. So: 26px travel, opacity, zero scale, colour-only on hover.
   Every technique is @supports- or IO-gated and every one has a final state
   that is already correct if nothing ever fires. */

/* #1 REVEAL — staggered entrance */
.rv{opacity:0;transform:translateY(26px);
  transition:opacity .62s var(--ease),transform .62s var(--ease);
  transition-delay:var(--d,0ms)}
.rv.in{opacity:1;transform:none}

/* #2 REVEAL — hairline rules draw in under section heads */
.drawline{height:1px;background:var(--line-2);transform:scaleX(0);
  transform-origin:0 50%;transition:transform .8s var(--ease) .1s}
.drawline.in{transform:scaleX(1)}

/* #3 REVEAL — the mastery curve draws itself */
.plot .curve{stroke-dasharray:var(--len,600);stroke-dashoffset:var(--len,600);
  transition:stroke-dashoffset 1.5s var(--ease) .25s}
.in .plot .curve,.plot.in .curve{stroke-dashoffset:0}

/* #4 TRANSFORM — the plate parallaxes against its own frame */
@keyframes plate-par{from{translate:0 -14px}to{translate:0 14px}}
@supports (animation-timeline:view()){
  figure.plate img{animation:plate-par linear both;animation-timeline:view();
    animation-range:cover 0% cover 100%}
}

/* #5 TRANSFORM — the tint band's grid drifts, so the ground has depth
   without anything moving that carries meaning */
@keyframes grid-drift{from{background-position:0 -30px}to{background-position:0 30px}}
@supports (animation-timeline:view()){
  .band--drift{animation:grid-drift linear both;animation-timeline:view();
    animation-range:cover 0% cover 100%}
}

/* #6 micro — hover, colour only (measured: the reference transforms nothing) */
/* implemented on .btn / .nav-links above */

/* #7 REVEAL — table rows cascade */
tbody.rv-rows tr{opacity:0;transform:translateY(14px);
  transition:opacity .5s var(--ease),transform .5s var(--ease);
  transition-delay:var(--d,0ms)}
tbody.rv-rows.in tr{opacity:1;transform:none}

/* #8 TRANSFORM — knowledge-graph nodes light by scroll position (JS writes
   --lit; CSS does the work) */
.kgraph .node{transition:fill .45s var(--ease),stroke .45s var(--ease)}

/* #9 micro — the gate readout ticks */
.gate-read dd{transition:color .25s var(--ease)}

@media (prefers-reduced-motion:reduce){
  .rv,.drawline,tbody.rv-rows tr{transition:none!important;
    opacity:1!important;transform:none!important}
  .plot .curve{transition:none!important;stroke-dashoffset:0!important}
  figure.plate img,.band--drift{animation:none!important;translate:none!important}
  .sigma-stage{transition:none}
}

/* ── responsive ────────────────────────────────────────────────────*/
@media (max-width:760px){
  :root{--measure:100%}
  .nav-here{display:none}
  .nav-links a{padding:.42rem .48rem;font-size:.86rem}
  .hero{padding-top:calc(56px + 3.2rem)}
  .stats{grid-template-columns:repeat(auto-fit,minmax(7.5rem,1fr))}
}
@media (max-width:420px){
  .nav-links a:not(.btn){display:none}
  .inst-head{flex-wrap:wrap;gap:.4rem}
}