/* ── yotalab Articles · Apple-style ── */
:root{
  --bg:#ffffff;
  --parchment:#f5f5f7;
  --ink:#1d1d1f;
  --ink-muted:rgba(0,0,0,0.8);
  --ink-faint:rgba(0,0,0,0.56);
  --ink-fine:rgba(0,0,0,0.48);
  --sub:#6e6e73;
  --tile-dark:#272729;
  --tile-dark-2:#2a2a2c;
  --tile-dark-3:#252527;
  --hairline:rgba(0,0,0,0.08);
  --hairline-soft:rgba(0,0,0,0.04);
  --action:#0066cc;
  --action-bright:#0071e3;
  --sky:#2997ff;
}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  font-family:system-ui,-apple-system,BlinkMacSystemFont,"SF Pro Text","Helvetica Neue",Helvetica,Arial,"Hiragino Sans","ヒラギノ角ゴシック",sans-serif;
  background:var(--bg);
  color:var(--ink);
  -webkit-font-smoothing:antialiased;
  font-size:17px;
  line-height:1.47;
  letter-spacing:-0.022em;
}
a{text-decoration:none;color:inherit}
img{max-width:100%;display:block}

/* ── Display font for headings ── */
h1,h2,h3,h4{
  font-family:system-ui,-apple-system,BlinkMacSystemFont,"SF Pro Display","Helvetica Neue",Helvetica,Arial,"Hiragino Sans",sans-serif;
  font-weight:600;
  color:var(--ink);
}

/* ── Global Nav (compact, frosted) ── */
nav.site-nav{
  position:fixed;top:0;left:0;right:0;z-index:100;
  background:rgba(245,245,247,0.8);
  backdrop-filter:saturate(180%) blur(20px);
  -webkit-backdrop-filter:saturate(180%) blur(20px);
  border-bottom:1px solid var(--hairline);
}
.nav-inner{
  max-width:980px;margin:0 auto;padding:0 22px;
  height:48px;display:flex;align-items:center;justify-content:space-between;
}
.logo{font-size:21px;font-weight:600;color:var(--ink);letter-spacing:-0.022em}
.nav-links{display:flex;gap:28px;list-style:none}
.nav-links a{font-size:14px;color:var(--sub);transition:color .2s;letter-spacing:-0.016em}
.nav-links a:hover{color:var(--ink)}
.nav-links a.active{color:var(--ink);font-weight:600}

/* ── Progress Bar (subtle) ── */
.progress-bar{
  position:fixed;top:0;left:0;height:2px;
  background:var(--action);
  width:0;z-index:1000;transition:width .05s linear;
}

/* ── Article Hero ── */
.article-hero{
  padding:160px 24px 96px;
  text-align:center;
  background:var(--parchment);
}
.article-hero .eyebrow{
  font-size:14px;font-weight:600;color:var(--action);
  letter-spacing:-0.016em;margin-bottom:14px;
}
.article-hero h1{
  font-size:clamp(40px,6.4vw,56px);
  font-weight:600;line-height:1.07;
  letter-spacing:-0.022em;
  max-width:780px;margin:0 auto;
}
.article-hero .lead{
  font-size:clamp(19px,2.4vw,24px);
  font-weight:400;line-height:1.5;
  color:var(--ink);
  margin:24px auto 0;max-width:680px;
  letter-spacing:-0.019em;
}
.article-hero .series-tag{
  display:inline-block;margin-top:32px;
  font-size:14px;color:var(--sub);
  letter-spacing:-0.016em;
}
.article-hero .series-tag strong{color:var(--ink);font-weight:600}

/* ── Tile (full-bleed, alternating) ── */
.tile{width:100%;padding:80px 22px}
.tile-light{background:var(--bg)}
.tile-soft{background:var(--parchment)}
.tile-dark{background:var(--tile-dark);color:#fff}
.tile-dark h1,.tile-dark h2,.tile-dark h3,.tile-dark h4{color:#fff}
.tile-dark p,.tile-dark li{color:rgba(255,255,255,0.92)}
.tile-dark a{color:var(--sky)}
.tile-dark .section-eyebrow{color:var(--sky)}
.tile-dark .callout{background:rgba(255,255,255,0.04);border-color:rgba(255,255,255,0.08)}
.tile-dark .callout-title{color:var(--sky)}
.tile-dark .callout cite{color:rgba(255,255,255,0.5)}
.tile-dark strong{color:#fff}

.tile-inner{max-width:780px;margin:0 auto}

/* ── Section structure ── */
.section-eyebrow{
  font-size:14px;font-weight:600;color:var(--action);
  letter-spacing:-0.016em;margin-bottom:16px;
}
.section h2{
  font-size:clamp(28px,4vw,34px);
  font-weight:600;line-height:1.18;
  letter-spacing:-0.011em;
  margin-bottom:24px;
}
.section h3{
  font-size:21px;font-weight:600;line-height:1.19;
  letter-spacing:-0.011em;
  margin:48px 0 14px;
}
.section h4{
  font-size:17px;font-weight:600;
  margin:24px 0 8px;letter-spacing:-0.022em;
}
.section p{
  font-size:17px;font-weight:400;line-height:1.47;
  letter-spacing:-0.022em;
  color:var(--ink);
  margin-bottom:18px;
}
.section p strong{font-weight:600;color:var(--ink)}
.section .lead{
  font-size:21px;font-weight:400;line-height:1.38;
  letter-spacing:-0.011em;
  color:var(--ink);
  margin-bottom:28px;
}
.section a{color:var(--action)}
.section a:hover{text-decoration:underline}

/* ── Callout (Note / Source / Tip) ── */
.callout{
  background:var(--parchment);
  border:1px solid var(--hairline);
  border-radius:18px;
  padding:24px 28px;
  margin:28px 0;
}
.callout-title{
  font-size:13px;font-weight:600;color:var(--action);
  letter-spacing:-0.014em;margin-bottom:8px;
  text-transform:none;
}
.callout p{font-size:15px;line-height:1.55;margin-bottom:8px;color:var(--ink-muted)}
.callout p:last-child{margin-bottom:0}
.callout cite{
  display:block;font-size:12px;color:var(--ink-fine);
  margin-top:10px;font-style:normal;letter-spacing:-0.012em;
}

/* ── Compare ── */
.compare{
  display:grid;grid-template-columns:1fr 1fr;gap:14px;margin:28px 0;
}
@media (max-width:640px){.compare{grid-template-columns:1fr}}
.compare-card{
  padding:24px 26px;background:var(--bg);
  border:1px solid var(--hairline);border-radius:18px;
}
.compare-label{
  font-size:12px;font-weight:600;color:var(--sub);
  letter-spacing:-0.012em;margin-bottom:10px;
}
.compare-card.after .compare-label{color:var(--action)}
.compare-card h4{font-size:16px;font-weight:600;margin:0 0 8px;color:var(--ink)}
.compare-card p{font-size:15px;line-height:1.5;color:var(--ink-muted);margin:0}

/* ── Timeline ── */
.timeline{margin:36px 0;position:relative}
.timeline::before{
  content:'';position:absolute;top:6px;bottom:6px;left:74px;width:1px;
  background:var(--hairline);
}
.timeline-item{
  display:grid;grid-template-columns:74px 1fr;gap:32px;
  padding:18px 0;align-items:baseline;position:relative;
  opacity:0;transform:translateY(8px);transition:all .5s ease;
}
.timeline-item.visible{opacity:1;transform:translateY(0)}
.timeline-item::before{
  content:'';position:absolute;left:71px;top:24px;
  width:7px;height:7px;background:var(--bg);
  border:1.5px solid var(--ink-faint);border-radius:50%;
  z-index:1;transition:all .4s ease;
}
.timeline-item.visible::before{background:var(--action);border-color:var(--action)}
.timeline-year{
  font-weight:600;font-size:15px;color:var(--action);
  text-align:right;padding-right:16px;letter-spacing:-0.016em;
  font-feature-settings:"tnum";
}
.timeline-content h4{margin:0 0 4px;font-size:17px;font-weight:600;color:var(--ink)}
.timeline-content p{margin:0;font-size:15px;color:var(--ink-muted);line-height:1.55}
@media (max-width:640px){
  .timeline::before{left:42px}
  .timeline-item{grid-template-columns:42px 1fr;gap:18px}
  .timeline-item::before{left:39px}
  .timeline-year{font-size:13px;padding-right:8px}
}

/* ── Skill levels ── */
.skill-levels{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;margin:32px 0}
@media (max-width:720px){.skill-levels{grid-template-columns:1fr}}
.skill-level{
  background:var(--bg);padding:28px 22px;
  border:1px solid var(--hairline);text-align:center;
  border-radius:18px;
}
.skill-icon{
  display:flex;justify-content:center;align-items:center;
  height:36px;margin-bottom:14px;color:var(--ink);
}
.skill-icon svg{width:32px;height:32px}
.skill-bar{height:4px;background:var(--hairline-soft);border-radius:2px;margin:14px 0;overflow:hidden}
.skill-fill{height:100%;background:var(--action);width:0;transition:width 1.5s cubic-bezier(.4,0,.2,1)}
.skill-name{font-weight:600;font-size:15px;margin-bottom:6px;color:var(--ink)}
.skill-desc{font-size:13px;color:var(--sub);line-height:1.5}

/* ── Survey ── */
.survey{
  margin:28px 0;background:var(--bg);
  padding:28px;border:1px solid var(--hairline);
  border-radius:18px;
}
.survey-title{
  font-size:14px;font-weight:600;color:var(--ink);
  margin-bottom:20px;padding-bottom:14px;
  border-bottom:1px solid var(--hairline);
  letter-spacing:-0.014em;
}
.survey-row{margin-bottom:18px}
.survey-row:last-child{margin-bottom:0}
.survey-label{
  display:flex;justify-content:space-between;
  font-size:14px;margin-bottom:8px;color:var(--ink);
}
.survey-pct{font-weight:600;color:var(--action);font-feature-settings:"tnum"}
.survey-bar{height:6px;background:var(--hairline-soft);border-radius:3px;overflow:hidden}
.survey-fill{
  height:100%;background:var(--action);
  width:0;transition:width 1.4s cubic-bezier(.4,0,.2,1);
}
.survey-note{font-size:12px;color:var(--ink-fine);margin-top:14px;line-height:1.5}

/* ── Code Example ── */
.example{
  background:var(--tile-dark);color:#e8eaed;
  padding:22px 26px;border-radius:18px;margin:22px 0;
  font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;
  font-size:14px;line-height:1.7;
  overflow-x:auto;
}
.example .comment{color:rgba(255,255,255,0.45);font-style:italic}
.example .highlight{color:#7fbcff;font-weight:600}
.example .arrow{color:rgba(255,255,255,0.55);margin:0 8px}
.example .key{color:#a5d6ff}

/* ── Params (parameter list) ── */
.params{
  margin:24px 0;background:var(--bg);
  border:1px solid var(--hairline);border-radius:18px;
  overflow:hidden;
}
.params .param-row{
  display:grid;
  grid-template-columns:160px 80px 1fr;
  gap:18px;align-items:baseline;
  padding:18px 24px;
  border-bottom:1px solid var(--hairline-soft);
}
.params .param-row:last-child{border-bottom:none}
.param-name{
  font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;
  font-size:14px;font-weight:600;color:var(--ink);
  letter-spacing:-0.012em;
}
.param-value{
  font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;
  font-size:15px;font-weight:600;color:var(--action);
  font-feature-settings:"tnum";margin:0;
}
.param-desc{
  font-size:14px;line-height:1.5;color:var(--ink-muted);margin:0;
  letter-spacing:-0.014em;
}
@media (max-width:640px){
  .params .param-row{
    grid-template-columns:1fr auto;gap:6px 14px;
    padding:16px 18px;
  }
  .param-desc{grid-column:1 / -1}
}

/* ── Flow (stage → stage → stage) ── */
.flow{
  display:grid;
  grid-template-columns:1fr auto 1fr auto 1fr;
  gap:14px;align-items:stretch;
  margin:28px 0;
}
.flow-stage{
  background:var(--bg);border:1px solid var(--hairline);
  border-radius:18px;padding:20px 18px;text-align:center;
  display:flex;flex-direction:column;justify-content:center;gap:8px;
}
.flow-label{
  font-size:12px;font-weight:600;color:var(--sub);
  letter-spacing:-0.012em;
}
.flow-value{
  font-size:20px;font-weight:600;color:var(--ink);
  letter-spacing:-0.014em;
}
.flow-value.mono{
  font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;
  font-feature-settings:"tnum";
}
.flow-value.accent{color:var(--action)}
.flow-arrow{
  align-self:center;font-size:20px;color:var(--ink-faint);font-weight:400;
}
@media (max-width:640px){
  .flow{grid-template-columns:1fr}
  .flow-arrow{transform:rotate(90deg);justify-self:center}
}

/* ── Equation (visual math expression) ── */
.equation{
  display:flex;align-items:center;justify-content:center;
  flex-wrap:wrap;gap:10px;
  margin:32px 0;padding:28px 24px;
  background:var(--parchment);
  border:1px solid var(--hairline);border-radius:18px;
}
.eq-term{
  display:inline-block;padding:10px 18px;
  background:var(--bg);border:1px solid var(--hairline);
  border-radius:11px;
  font-size:18px;font-weight:600;color:var(--ink);
  letter-spacing:-0.014em;
}
.eq-term.eq-result{
  background:var(--action);color:#fff;border-color:var(--action);
}
.eq-op{
  font-size:22px;font-weight:400;color:var(--ink-faint);
  font-feature-settings:"tnum";
}

/* ── QA Card (training data examples) ── */
.qa-card{
  background:var(--bg);border:1px solid var(--hairline);
  border-radius:18px;padding:24px 26px;margin:20px 0;
}
.qa-head{
  display:flex;align-items:center;gap:12px;
  padding-bottom:14px;margin-bottom:14px;
  border-bottom:1px solid var(--hairline-soft);
}
.qa-num{
  font-size:13px;font-weight:600;color:var(--ink);
  letter-spacing:-0.014em;
}
.qa-tag{
  font-size:12px;font-weight:600;color:var(--action);
  background:rgba(0,102,204,0.08);
  padding:3px 10px;border-radius:980px;letter-spacing:-0.012em;
}
.qa-row{
  display:grid;grid-template-columns:32px 1fr;gap:14px;
  align-items:start;margin-bottom:10px;
}
.qa-row p{
  margin:0;font-size:15px;line-height:1.55;color:var(--ink);
  letter-spacing:-0.014em;
}
.qa-label{
  display:inline-flex;align-items:center;justify-content:center;
  width:26px;height:26px;border-radius:50%;
  font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;
  font-size:12px;font-weight:600;
}
.qa-label.q{background:var(--parchment);color:var(--ink-muted)}
.qa-label.a{background:var(--action);color:#fff}
.qa-note{
  margin-top:14px;padding-top:12px;
  border-top:1px solid var(--hairline-soft);
  font-size:13px;color:var(--ink-faint);
  letter-spacing:-0.012em;
}

/* ── Tokenizer ── */
.tokenizer-demo{
  background:var(--bg);border:1px solid var(--hairline);
  padding:24px;margin:28px 0;border-radius:18px;
}
.tokenizer-input{
  font-size:17px;font-weight:600;
  padding:14px 18px;background:var(--parchment);
  border-radius:12px;margin-bottom:16px;text-align:center;
  letter-spacing:-0.022em;
}
.tokenizer-arrow{text-align:center;font-size:18px;color:var(--ink-faint);margin:8px 0;animation:arrowPulse 2s infinite ease-in-out}
@keyframes arrowPulse{0%,100%{transform:translateY(0);opacity:.6}50%{transform:translateY(3px);opacity:1}}
.token-row{display:flex;flex-wrap:wrap;gap:6px;justify-content:center;margin:14px 0}
.token{
  display:inline-flex;flex-direction:column;align-items:center;
  background:var(--bg);border:1px solid var(--hairline);
  padding:9px 13px;border-radius:11px;min-width:56px;
  position:relative;animation:tokenPop .5s ease backwards;
}
.token:nth-child(1){animation-delay:.1s}.token:nth-child(2){animation-delay:.2s}.token:nth-child(3){animation-delay:.3s}.token:nth-child(4){animation-delay:.4s}.token:nth-child(5){animation-delay:.5s}.token:nth-child(6){animation-delay:.6s}
@keyframes tokenPop{from{opacity:0;transform:translateY(8px) scale(.95)}to{opacity:1;transform:translateY(0) scale(1)}}
.token-text{font-weight:600;font-size:14.5px;color:var(--ink)}
.token-id{font-family:ui-monospace,SFMono-Regular,Menlo,monospace;font-size:11px;color:var(--ink-fine);margin-top:3px;font-feature-settings:"tnum"}
.token.color-1,.token.color-2,.token.color-3,.token.color-4,.token.color-5{
  /* Apple-style: keep tokens neutral, color-coding via subtle bg only */
  background:var(--parchment);
}
.tokenizer-result{text-align:center;margin-top:14px;color:var(--action);font-weight:600;font-size:14px}

/* ── Probability list ── */
.prob-list{
  margin:24px 0;background:var(--bg);
  padding:24px;border:1px solid var(--hairline);
  border-radius:18px;
}
.prob-row{display:grid;grid-template-columns:130px 1fr 60px;gap:14px;align-items:center;margin-bottom:12px}
.prob-row:last-child{margin-bottom:0}
.prob-word{font-weight:600;font-size:15px;color:var(--ink)}
.prob-bar{height:8px;background:var(--hairline-soft);border-radius:4px;overflow:hidden}
.prob-fill{height:100%;background:var(--action);width:0;transition:width 1.5s cubic-bezier(.4,0,.2,1);opacity:0.85}
.prob-fill.high{opacity:1}
.prob-fill.mid{opacity:0.7}
.prob-fill.low{opacity:0.45}
.prob-pct{font-weight:600;text-align:right;font-size:14px;color:var(--action);font-feature-settings:"tnum"}

/* ── Generation Flow ── */
.generation-flow{
  margin:32px 0;background:var(--bg);
  padding:26px;border:1px solid var(--hairline);
  border-radius:18px;
}
.gen-step{
  display:flex;align-items:center;gap:14px;
  padding:11px 0;border-bottom:1px solid var(--hairline-soft);
  opacity:0;transform:translateX(-10px);transition:all .5s ease;
}
.gen-step.visible{opacity:1;transform:translateX(0)}
.gen-step:last-child{border-bottom:none}
.gen-step-num{font-family:ui-monospace,SFMono-Regular,Menlo,monospace;font-size:11px;color:var(--ink-fine);font-weight:600;min-width:36px;font-feature-settings:"tnum"}
.gen-step-text{flex:1;font-size:15px;color:var(--ink);line-height:1.55}
.gen-step-text .gen-new{
  color:#fff;background:var(--action);
  padding:1px 8px;border-radius:5px;font-weight:600;
  animation:newWordPop .6s ease;
}
@keyframes newWordPop{0%{transform:scale(.85);opacity:0}60%{transform:scale(1.05)}100%{transform:scale(1);opacity:1}}
.gen-arrow{color:var(--ink-faint);font-family:ui-monospace,SFMono-Regular,Menlo,monospace}

/* ── Vector Viz ── */
.vector-viz{
  background:var(--bg);border:1px solid var(--hairline);
  padding:24px;margin:32px 0;border-radius:18px;
}
.vector-viz-header{
  display:flex;justify-content:space-between;align-items:baseline;
  margin-bottom:16px;padding-bottom:14px;
  border-bottom:1px solid var(--hairline);
  flex-wrap:wrap;gap:12px;
}
.vector-viz-title{
  font-size:13px;font-weight:600;color:var(--ink);
  letter-spacing:-0.014em;
}
.vector-viz-controls{display:flex;gap:6px;flex-wrap:wrap}
.viz-btn{
  font-size:13px;letter-spacing:-0.014em;padding:7px 14px;
  background:var(--bg);border:1px solid var(--hairline);
  color:var(--ink-muted);cursor:pointer;transition:all .25s;
  border-radius:980px;font-weight:400;font-family:inherit;
}
.viz-btn:hover{border-color:var(--action);color:var(--action)}
.viz-btn:active{transform:scale(0.97)}
.viz-btn.active{
  background:var(--action);color:#fff;border-color:var(--action);
}
.vector-stage{
  position:relative;width:100%;aspect-ratio:16/11;
  background:var(--parchment);
  border:1px solid var(--hairline);overflow:hidden;border-radius:12px;
}
.vec-axis{position:absolute;background:var(--ink-faint);opacity:.35}
.vec-axis-x{left:0;right:0;bottom:12%;height:1px}
.vec-axis-y{top:0;bottom:0;left:12%;width:1px}
.vec-axis-label{
  position:absolute;font-size:11px;color:var(--sub);
}
.vec-axis-label.x{right:14px;bottom:14%}
.vec-axis-label.y{left:14%;top:14px}
.vec-point{
  position:absolute;width:12px;height:12px;border-radius:50%;
  background:var(--ink-faint);transform:translate(-50%,50%);
  transition:left 1.5s cubic-bezier(.4,0,.2,1),bottom 1.5s cubic-bezier(.4,0,.2,1),background .6s,box-shadow .6s;
  z-index:3;
}
.vec-point.highlight{
  background:var(--action);
  box-shadow:0 0 0 5px rgba(0,102,204,0.15);
}
.vec-point.dim{opacity:.4}
.vec-point.target{
  background:#fff;border:2px solid var(--action);
  box-shadow:0 0 0 4px rgba(0,102,204,0.12);
}
.vec-label.target{color:var(--action);font-weight:600}
.vec-label{
  position:absolute;font-size:12px;font-weight:500;color:var(--ink);
  transform:translate(10px,50%);white-space:nowrap;
  transition:left 1.5s cubic-bezier(.4,0,.2,1),bottom 1.5s cubic-bezier(.4,0,.2,1),color .6s;
  pointer-events:none;z-index:4;letter-spacing:-0.014em;
  text-shadow:0 0 4px var(--parchment),0 0 8px var(--parchment);
}
.vec-label.highlight{color:var(--action);font-weight:600}
.vec-label.dim{opacity:.55}
.vec-trail{
  position:absolute;width:6px;height:6px;border-radius:50%;
  background:var(--action);transform:translate(-50%,50%);
  opacity:0;z-index:2;pointer-events:none;
}
.vec-trail.show{animation:trailFade 1.6s ease-out forwards}
@keyframes trailFade{0%{opacity:.5;transform:translate(-50%,50%) scale(1)}100%{opacity:0;transform:translate(-50%,50%) scale(.3)}}
.vector-caption{
  margin-top:16px;padding:14px 18px;
  background:var(--parchment);
  border-radius:12px;
  font-size:14px;line-height:1.6;color:var(--ink);
  min-height:54px;transition:background .4s;
}
.vector-caption.active{background:rgba(0,102,204,0.06)}
.vector-caption .step-num{
  font-family:ui-monospace,SFMono-Regular,Menlo,monospace;
  font-size:11px;color:var(--ink-fine);letter-spacing:0;
  display:block;margin-bottom:4px;font-weight:600;
}
.vector-caption.active .step-num{color:var(--action)}

/* ── Attention ── */
.attention-viz{
  background:var(--bg);border:1px solid var(--hairline);
  padding:24px;margin:28px 0;border-radius:18px;
}
.attention-sentence{display:flex;gap:6px;flex-wrap:wrap;margin-bottom:16px;justify-content:center}
.att-token{
  position:relative;padding:9px 13px;
  background:var(--bg);border:1px solid var(--hairline);
  border-radius:11px;font-size:14px;font-weight:500;
  cursor:default;transition:all .5s ease;
  min-width:54px;text-align:center;color:var(--ink);
  letter-spacing:-0.014em;
}
.att-token.source{
  background:var(--ink);color:#fff;border-color:var(--ink);
}
.att-token .att-pct{
  display:block;font-family:ui-monospace,SFMono-Regular,Menlo,monospace;
  font-size:10px;margin-top:3px;opacity:.85;min-height:12px;font-feature-settings:"tnum";
}
.att-token[data-attention="high"]{background:var(--action);color:#fff;border-color:var(--action)}
.att-token[data-attention="mid"]{background:rgba(0,102,204,0.18);color:var(--action);border-color:rgba(0,102,204,0.3)}
.att-token[data-attention="low"]{opacity:.45}

/* ── Steps ── */
.steps{margin:32px 0;counter-reset:step}
.step{
  display:grid;grid-template-columns:60px 1fr;gap:24px;
  padding:24px 0;border-bottom:1px solid var(--hairline);
  counter-increment:step;
}
.step:last-child{border-bottom:none}
.step::before{
  content:counter(step,decimal-leading-zero);
  font-family:ui-monospace,SFMono-Regular,Menlo,monospace;
  font-size:24px;font-weight:600;color:var(--ink-faint);line-height:1;
  font-feature-settings:"tnum";
}
.step-content h4{margin:0 0 10px;font-size:17px;font-weight:600;color:var(--ink)}
.step-content p{margin:0;font-size:15px;color:var(--ink-muted);line-height:1.6}
.step-content p+p{margin-top:8px}

/* ── Stats ── */
.stats-grid{
  display:grid;
  grid-template-columns:repeat(auto-fit,minmax(160px,1fr));
  gap:14px;margin:32px 0;
}
.stat-card{
  background:var(--bg);border:1px solid var(--hairline);
  padding:22px;border-radius:18px;
}
.stat-value{
  font-size:28px;font-weight:600;color:var(--ink);
  display:block;margin-bottom:6px;line-height:1;
  letter-spacing:-0.022em;font-feature-settings:"tnum";
}
.stat-label{font-size:13px;color:var(--ink-muted);line-height:1.45}
.stat-source{font-size:11px;color:var(--ink-fine);margin-top:8px}

/* ── FFN ── */
.ffn-viz{
  background:var(--bg);border:1px solid var(--hairline);
  padding:28px;margin:32px 0;border-radius:18px;overflow:hidden;
}
.ffn-stages{
  display:grid;grid-template-columns:1fr auto 1.5fr auto 1fr;
  gap:14px;align-items:center;margin:18px 0;
}
@media (max-width:720px){.ffn-stages{grid-template-columns:1fr}.ffn-arrow{transform:rotate(90deg)}}
.ffn-stage{
  text-align:center;padding:18px 12px;
  background:var(--parchment);border-radius:12px;position:relative;
}
.ffn-stage.expanded{
  background:rgba(0,102,204,0.08);
  padding:22px 12px;
}
.ffn-stage-label{
  font-size:11px;color:var(--action);letter-spacing:-0.012em;
  margin-bottom:10px;font-weight:600;
}
.ffn-stage-dims{display:flex;justify-content:center;gap:4px;margin:10px 0}
.ffn-dim{width:6px;height:20px;background:var(--action);border-radius:2px;opacity:0.6}
.ffn-dim.expanded-dim{height:30px;opacity:1}
.ffn-dim.zeroed{background:var(--hairline);height:6px;align-self:center;opacity:1}
.ffn-stage-text{font-size:12px;color:var(--ink-muted);margin-top:6px;line-height:1.45}
.ffn-arrow{font-size:18px;color:var(--ink-faint);font-weight:400}

/* ── Training Viz ── */
.training-viz{
  background:var(--bg);border:1px solid var(--hairline);
  padding:28px;margin:32px 0;border-radius:18px;
}
.training-flow{
  display:grid;grid-template-columns:1fr auto 1fr auto 1fr;
  gap:14px;align-items:stretch;
}
@media (max-width:720px){.training-flow{grid-template-columns:1fr}.training-arrow{transform:rotate(90deg);margin:8px auto}}
.training-box{
  background:var(--parchment);padding:20px;border-radius:12px;
  text-align:center;
}
.training-box-label{
  font-size:11px;color:var(--action);letter-spacing:-0.012em;
  margin-bottom:10px;font-weight:600;
}
.training-box-content{font-size:13px;color:var(--ink);line-height:1.55}
.training-arrow{font-size:18px;color:var(--ink-faint);align-self:center;text-align:center}
.training-params{display:flex;justify-content:center;flex-wrap:wrap;gap:4px;margin-top:8px}
.param-dial{width:10px;height:10px;border-radius:50%;background:var(--action);opacity:.55;animation:paramAdjust 1.8s infinite ease-in-out}
.param-dial:nth-child(odd){animation-delay:.3s}
.param-dial:nth-child(3n){animation-delay:.6s}
.param-dial:nth-child(5n){animation-delay:.9s}
@keyframes paramAdjust{0%,100%{transform:scale(1);opacity:.4}50%{transform:scale(1.25);opacity:1}}

/* ── Blockquote ── */
blockquote{
  padding:0 0 0 24px;margin:32px 0;
  border-left:2px solid var(--action);
  font-size:21px;font-weight:400;color:var(--ink);
  line-height:1.4;letter-spacing:-0.011em;
}

/* ── Link list ── */
.link-list{margin:20px 0;list-style:none}
.link-list li{
  padding:14px 0;border-bottom:1px solid var(--hairline);
  font-size:15px;
}
.link-list li:last-child{border-bottom:none}
.link-list a{color:var(--action);font-weight:400}
.link-list a:hover{text-decoration:underline}

/* ── Summary section ── */
.summary{
  background:var(--tile-dark);color:#fff;
  padding:96px 22px;
}
.summary .tile-inner{max-width:780px;margin:0 auto}
.summary .section-eyebrow{color:var(--sky)}
.summary h2{color:#fff;font-size:34px;margin-bottom:24px;font-weight:600;letter-spacing:-0.011em}
.summary p{color:rgba(255,255,255,0.85);font-size:17px;line-height:1.55;margin-bottom:18px}
.summary p strong{color:#fff;font-weight:600}
.summary-cta{
  margin-top:36px;padding-top:28px;
  border-top:1px solid rgba(255,255,255,0.15);
  font-size:19px;line-height:1.5;color:rgba(255,255,255,0.92);font-weight:400;
}

/* ── Prev/Next chapter nav ── */
.chapter-nav{
  max-width:980px;margin:0 auto;
  padding:64px 22px 96px;
  display:grid;grid-template-columns:1fr 1fr;gap:16px;
}
@media (max-width:680px){.chapter-nav{grid-template-columns:1fr}}
.chapter-nav-card{
  display:block;
  background:var(--bg);
  border:1px solid var(--hairline);border-radius:18px;
  padding:24px 28px;
  transition:border-color .2s;
  color:inherit;
}
.chapter-nav-card:hover{border-color:var(--action)}
.chapter-nav-card.disabled{opacity:0.4;pointer-events:none}
.chapter-nav-card .label{
  font-size:13px;color:var(--sub);font-weight:400;
  letter-spacing:-0.014em;margin-bottom:8px;
  display:flex;align-items:center;gap:6px;
}
.chapter-nav-card.next{text-align:right}
.chapter-nav-card.next .label{justify-content:flex-end}
.chapter-nav-card .ch-num{
  display:block;font-size:13px;color:var(--action);font-weight:600;margin-bottom:4px;
  letter-spacing:-0.014em;
}
.chapter-nav-card .ch-title{
  display:block;font-size:18px;font-weight:600;color:var(--ink);
  letter-spacing:-0.022em;line-height:1.3;
}
.chapter-nav-card .arrow{
  display:inline-block;transition:transform .25s;color:var(--action);
}
.chapter-nav-card:hover .arrow{transform:translateX(4px)}
.chapter-nav-card.prev:hover .arrow{transform:translateX(-4px)}

/* ── Articles index page (categories) ── */
.index-grid{
  max-width:980px;margin:0 auto;
  padding:48px 22px 96px;
  display:grid;grid-template-columns:1fr 1fr;gap:20px;
}
@media (max-width:760px){.index-grid{grid-template-columns:1fr}}
.cat-card{
  display:block;background:var(--bg);
  border:1px solid var(--hairline);border-radius:18px;
  padding:36px 32px;color:inherit;
  transition:border-color .2s,transform .25s;
}
.cat-card:hover{border-color:var(--action)}
.cat-card:active{transform:scale(0.99)}
.cat-card.muted{opacity:0.55;pointer-events:none}
.cat-card .topic{
  font-size:13px;font-weight:600;color:var(--action);
  letter-spacing:-0.014em;margin-bottom:14px;
}
.cat-card.muted .topic{color:var(--sub)}
.cat-card h2{
  font-size:28px;font-weight:600;letter-spacing:-0.022em;
  margin-bottom:10px;line-height:1.18;
}
.cat-card p{
  font-size:15px;line-height:1.5;color:var(--ink-muted);margin-bottom:18px;
}
.cat-card .count{
  font-size:13px;color:var(--sub);letter-spacing:-0.014em;
}
.cat-card .arrow{
  display:inline-block;color:var(--action);font-weight:600;font-size:14px;
  margin-top:10px;
}

/* ── Category page article tile ── */
.article-list{
  max-width:780px;margin:0 auto;
  padding:48px 22px 96px;
}
.article-card{
  display:block;background:var(--bg);
  border:1px solid var(--hairline);border-radius:18px;
  padding:36px 36px;color:inherit;
  margin-bottom:18px;
  transition:border-color .2s;
}
.article-card:hover{border-color:var(--action)}
.article-card .topic{
  font-size:13px;font-weight:600;color:var(--action);
  letter-spacing:-0.014em;margin-bottom:12px;
}
.article-card h2{
  font-size:28px;font-weight:600;letter-spacing:-0.022em;
  line-height:1.18;margin-bottom:10px;
}
.article-card p{
  font-size:15px;line-height:1.5;color:var(--ink-muted);margin-bottom:18px;
}
.article-card .meta{
  font-size:13px;color:var(--sub);letter-spacing:-0.014em;margin-bottom:16px;
}
.article-card .chapter-toc{
  margin-top:18px;padding-top:18px;
  border-top:1px solid var(--hairline);
  list-style:none;
}
.article-card .chapter-toc li{
  display:flex;align-items:baseline;gap:14px;
  padding:10px 0;
  border-bottom:1px solid var(--hairline-soft);
  font-size:14px;
}
.article-card .chapter-toc li:last-child{border-bottom:none}
.article-card .chapter-toc .ch-num{
  font-family:ui-monospace,SFMono-Regular,Menlo,monospace;
  font-size:11px;color:var(--ink-fine);font-weight:600;
  min-width:38px;font-feature-settings:"tnum";
}
.article-card .chapter-toc a{
  color:var(--ink);flex:1;letter-spacing:-0.016em;
}
.article-card .chapter-toc a:hover{color:var(--action)}
.article-card .chapter-toc .ch-meta{
  font-size:12px;color:var(--sub);margin-left:auto;letter-spacing:-0.012em;
}

/* ── Footer ── */
footer.site-footer{
  background:var(--parchment);
  padding:32px 22px;
  border-top:1px solid var(--hairline);
}
.footer-inner{
  max-width:980px;margin:0 auto;
  display:flex;justify-content:space-between;align-items:center;
  flex-wrap:wrap;gap:12px;
}
footer.site-footer p{font-size:12px;color:var(--ink-fine);letter-spacing:-0.012em}
footer.site-footer a{font-size:12px;color:var(--ink-fine);letter-spacing:-0.012em}
footer.site-footer a:hover{color:var(--ink)}
.footer-links{display:flex;gap:20px}

@media (max-width:680px){
  .footer-inner{flex-direction:column;text-align:center}
  .article-hero{padding:120px 22px 72px}
  .tile{padding:64px 22px}
  .article-card{padding:28px 24px}
  .cat-card{padding:28px 24px}
}