/* ═══════════════════════════════════════════════════════════════════
   lab.css — shared chrome for the Lab series
   Extracted from convolution-lab.html so each new lab is content,
   not scaffolding. Lab-specific rules stay in each lab's own <style>.
   ═══════════════════════════════════════════════════════════════════ */

:root{
  --paper:#f4ede0; --paper-dark:#ebe1cf;
  --ink:#1a1a1a; --ink-soft:#3d3d3d; --ink-light:#6b6b6b;
  --vermillion:#b8412e; --vermillion-dark:#8a2e20;
  --sage:#6b7a5a; --gold:#a88848;
  --line:rgba(26,26,26,0.12); --card:rgba(255,255,255,0.5);
  /* one easing vocabulary, shared with index.html */
  --ease-out:cubic-bezier(0.22,0.61,0.24,1);
  --ease-soft:cubic-bezier(0.4,0,0.2,1);
}

*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;background:var(--paper);color:var(--ink);
  font-family:'Cormorant Garamond','Noto Serif JP',serif;font-size:1.06rem;line-height:1.75;
  background-image:
    radial-gradient(ellipse at top right,rgba(184,65,46,.04),transparent 60%),
    radial-gradient(ellipse at bottom left,rgba(107,122,90,.05),transparent 60%);
  background-attachment:fixed;
}
.container{max-width:1080px;margin:0 auto;padding:0 2rem}

/* ═════ top bar ═════ */
.top-bar{display:flex;justify-content:space-between;align-items:center;padding:1.1rem 3rem;
  position:sticky;top:0;z-index:100;background:rgba(244,237,224,.88);backdrop-filter:blur(8px);
  border-bottom:1px solid var(--line)}
.brand{font-size:1.05rem;letter-spacing:.04em;text-decoration:none;color:var(--ink)}
.brand em{font-style:italic;color:var(--vermillion)}
.nav-links{display:flex;gap:1.6rem;align-items:center}
.nav-links a{font-family:'Inter',sans-serif;font-size:.66rem;letter-spacing:.22em;text-transform:uppercase;
  color:var(--ink-soft);text-decoration:none;position:relative;transition:color .3s var(--ease-soft)}
.nav-links a::after{content:"";position:absolute;bottom:-4px;left:0;right:0;height:1px;
  background:var(--vermillion);transform:scaleX(0);transform-origin:left;transition:transform .3s var(--ease-out)}
.nav-links a:hover{color:var(--ink)}
.nav-links a:hover::after{transform:scaleX(1)}
.nav-links a.here{color:var(--vermillion)}
.nav-links a.here::after{transform:scaleX(1)}

/* ═════ hero & sections ═════ */
.hero{padding:5rem 0 3rem;text-align:center}
.hero-kanji{font-family:'Noto Serif JP',serif;font-weight:300;font-size:1.05rem;color:var(--vermillion);
  letter-spacing:.5em;margin-bottom:1.8rem}
.hero h1{font-size:clamp(2.4rem,6vw,3.8rem);font-weight:400;margin:0;letter-spacing:-.01em;line-height:1.1}
.hero h1 em{font-style:italic;color:var(--vermillion)}
.hero-divider{width:90px;height:1px;background:var(--ink);margin:1.9rem auto}
.hero p{max-width:62ch;margin:0 auto;color:var(--ink-soft);font-size:1.12rem}

section{padding:3.2rem 0}
.section-heading{margin-bottom:2rem}
.section-num{font-family:'Inter',sans-serif;font-size:.62rem;letter-spacing:.3em;text-transform:uppercase;
  color:var(--ink-light);display:block;margin-bottom:.8rem}
.section-heading-kanji{font-family:'Noto Serif JP',serif;color:var(--vermillion);font-size:.9rem;
  letter-spacing:.5em;margin-bottom:.6rem}
.section-heading-text{font-size:2rem;font-weight:400;margin:0 0 1rem;letter-spacing:-.01em}
.section-heading-rule{width:100%;height:1px;background:var(--line)}
.lede{max-width:66ch;color:var(--ink-soft);margin:1.3rem 0 2rem}
.sub-h{font-family:'Cormorant Garamond',serif;font-size:1.4rem;font-weight:400;margin:2.8rem 0 .4rem}
.note{border-left:2px solid var(--vermillion);padding:.2rem 0 .2rem 1.1rem;margin:1.8rem 0 0;
  color:var(--ink-soft);max-width:68ch}

/* ═════ controls ═════ */
.label{font-family:'Inter',sans-serif;font-size:.62rem;letter-spacing:.22em;text-transform:uppercase;
  color:var(--ink-light);display:block;margin-bottom:.55rem}
.mono{font-family:'Inter',sans-serif;font-size:.82rem;letter-spacing:.02em}
.label .mono{text-transform:none;letter-spacing:.02em}
.chip{font-family:'Inter',sans-serif;font-size:.69rem;letter-spacing:.06em;border:1px solid var(--line);
  background:transparent;color:var(--ink-soft);padding:.35rem .85rem;cursor:pointer;transition:all .25s var(--ease-soft)}
.chip:hover:not(:disabled){border-color:var(--vermillion);color:var(--ink)}
.chip:disabled{opacity:.35;cursor:default}
.chip[aria-pressed="true"]{background:var(--vermillion);border-color:var(--vermillion);color:var(--paper)}
.chiprow{display:flex;flex-wrap:wrap;gap:.45rem}
.seg{display:flex;border:1px solid var(--line)}
.seg button{flex:1;font-family:'Inter',sans-serif;font-size:.74rem;border:0;background:transparent;
  color:var(--ink-soft);padding:.42rem .3rem;cursor:pointer;transition:all .25s var(--ease-soft);white-space:nowrap}
.seg button+button{border-left:1px solid var(--line)}
.seg button[aria-pressed="true"]{background:var(--ink);color:var(--paper)}
.seg button:disabled{opacity:.3;cursor:default}
button:focus-visible,input:focus-visible,a:focus-visible{outline:2px solid var(--vermillion);outline-offset:2px}
input[type=range]{accent-color:var(--vermillion);width:100%}
.controls{display:grid;grid-template-columns:repeat(auto-fit,minmax(158px,1fr));gap:1.4rem 1.6rem;margin-top:1.9rem}

.filebtn{position:relative;overflow:hidden;display:inline-block}
.filebtn input{position:absolute;inset:0;opacity:0;cursor:pointer}
.upload-msg{font-family:'Inter',sans-serif;font-size:.66rem;letter-spacing:.06em;color:var(--vermillion);
  display:block;max-width:22ch;margin-top:.5rem;opacity:0;transform:translateY(-3px);
  transition:opacity .4s var(--ease-soft),transform .4s var(--ease-out)}
.upload-msg.show{opacity:1;transform:none}

/* ═════ transport (playback) ═════ */
.transport{display:flex;align-items:center;gap:.7rem;flex-wrap:wrap;margin-top:1.8rem;
  padding:1rem 1.2rem;border:1px solid var(--line);background:var(--card)}
.transport button{font-family:'Inter',sans-serif;font-size:.75rem;border:1px solid var(--line);
  background:transparent;color:var(--ink);padding:.42rem .95rem;cursor:pointer;transition:all .25s var(--ease-soft)}
.transport button:hover:not(:disabled){border-color:var(--vermillion)}
.transport button:disabled{opacity:.32;cursor:default}
.transport .play{background:var(--ink);color:var(--paper);border-color:var(--ink);min-width:72px}
.counter{font-family:'Inter',sans-serif;font-size:.73rem;color:var(--ink-light);margin-left:auto}
.speed{display:flex;align-items:center;gap:.5rem;font-family:'Inter',sans-serif;font-size:.71rem;color:var(--ink-light)}
.speed input{width:84px}

/* ═════ equations ═════ */
.eqbox{border:1px solid var(--line);background:var(--card);padding:1.5rem 1.6rem;margin-bottom:2rem}
.eqmath{font-family:'Cormorant Garamond',serif;font-size:1.45rem;line-height:1.5;
  display:flex;flex-wrap:wrap;align-items:center;gap:.08rem}
.eqmath i{font-style:italic}
.sym{font-style:italic;transition:color .2s,background .2s;padding:0 .04em;border-radius:2px}
.sym.on{color:var(--vermillion);font-weight:500;background:rgba(184,65,46,.1)}
.sigma{display:inline-flex;flex-direction:column;align-items:center;justify-content:center;margin:0 .28rem;line-height:1}
.sigma .big{font-size:1.45em;line-height:.85}
.sigma small{font-family:'Inter',sans-serif;font-size:.34em;letter-spacing:0;color:var(--ink-light);white-space:nowrap}
.eqkey{display:flex;flex-wrap:wrap;gap:.4rem 1.4rem;margin-top:1.2rem;padding-top:1rem;
  border-top:1px solid var(--line);font-family:'Inter',sans-serif;font-size:.77rem;color:var(--ink-soft)}
.eqkey b{color:var(--vermillion);font-weight:500}
.eqgloss{font-size:1rem;color:var(--ink-soft);margin-top:.9rem;max-width:68ch}

/* ═════ numeric grids ═════ */
.stage{display:flex;flex-wrap:wrap;gap:2.6rem;align-items:flex-start}
.panel{flex:1 1 330px;min-width:0}
.panel h3{font-family:'Inter',sans-serif;font-size:.62rem;letter-spacing:.22em;text-transform:uppercase;
  color:var(--ink-light);font-weight:400;margin:0 0 .35rem}
.panel .sub{font-family:'Inter',sans-serif;font-size:.75rem;color:var(--ink-soft);margin:0 0 .9rem}
.gridwrap{position:relative;width:fit-content;max-width:100%}
.grid{display:grid;gap:3px}
.cell{border:1px solid var(--line);background:rgba(255,255,255,.55);display:flex;align-items:center;
  justify-content:center;font-family:'Inter',sans-serif;font-size:.78rem;color:var(--ink)}
.cell.pad{background:var(--paper-dark);color:var(--ink-light);border-style:dashed;font-size:.65rem}
.cell.tap{box-shadow:inset 0 0 0 1px var(--vermillion);border-color:var(--vermillion)}
.cell.here{background:var(--vermillion);color:var(--paper);border-color:var(--vermillion)}
.cell.here input{color:var(--paper)}
.cell input{width:100%;height:100%;border:0;background:transparent;text-align:center;font:inherit;
  color:inherit;padding:0;-moz-appearance:textfield}
.cell input::-webkit-outer-spin-button,.cell input::-webkit-inner-spin-button{-webkit-appearance:none;margin:0}
.probe{position:absolute;pointer-events:none;border:2px solid var(--vermillion);background:rgba(184,65,46,.09);
  transition:left .28s cubic-bezier(.4,.1,.2,1),top .28s cubic-bezier(.4,.1,.2,1),width .2s,height .2s}
.kernel{margin-top:1.8rem}

/* ═════ image blocks ═════ */
.imgrow{display:flex;flex-wrap:wrap;gap:1.8rem;align-items:flex-start}
.imgblock{display:flex;flex-direction:column;gap:.55rem}
.imgblock canvas{display:block;border:1px solid var(--line);background:var(--paper-dark);
  image-rendering:pixelated;width:224px;height:224px}
.imgblock.sm canvas{width:134px;height:134px}
.imgblock .cap{font-family:'Inter',sans-serif;font-size:.66rem;letter-spacing:.14em;
  text-transform:uppercase;color:var(--ink-light)}
.imgblock .dim{font-family:'Inter',sans-serif;font-size:.71rem;color:var(--ink-soft)}
.maps{display:flex;flex-wrap:wrap;gap:.85rem;margin-top:1.5rem}
.map{border:1px solid var(--line);background:transparent;padding:0;cursor:pointer;display:flex;
  flex-direction:column;transition:all .25s var(--ease-soft)}
.map canvas{display:block;width:94px;height:94px;image-rendering:pixelated}
.map span{font-family:'Inter',sans-serif;font-size:.59rem;letter-spacing:.07em;color:var(--ink-soft);
  padding:.35rem .25rem;text-align:center}
.map:hover{border-color:var(--vermillion)}
.map[aria-pressed="true"]{border-color:var(--vermillion);background:rgba(184,65,46,.08)}
.map[aria-pressed="true"] span{color:var(--vermillion)}
.kview{display:grid;gap:3px}
.kview div,.kview input{border:1px solid var(--line);background:rgba(255,255,255,.55);height:34px;width:34px;
  display:flex;align-items:center;justify-content:center;font-family:'Inter',sans-serif;font-size:.7rem;
  text-align:center;color:var(--ink);padding:0;-moz-appearance:textfield}
.kview input::-webkit-outer-spin-button,.kview input::-webkit-inner-spin-button{-webkit-appearance:none;margin:0}

/* ═════ scoreboards & bars ═════ */
.scoreboard{display:grid;grid-template-columns:repeat(auto-fit,minmax(112px,1fr));
  gap:1rem 1.2rem;margin-top:1.6rem;padding-top:1.4rem;border-top:1px solid var(--line)}
.score{display:flex;flex-direction:column;gap:.25rem}
.score .k{font-family:'Inter',sans-serif;font-size:.6rem;letter-spacing:.2em;
  text-transform:uppercase;color:var(--ink-light)}
.score .v{font-family:'Cormorant Garamond',serif;font-size:1.85rem;line-height:1.1;color:var(--ink)}
.score.hero-metric .v{color:var(--vermillion);font-size:2.3rem}
.score .n{font-family:'Inter',sans-serif;font-size:.67rem;color:var(--ink-light)}

.bars{margin-top:1.4rem;display:flex;flex-direction:column;gap:.7rem}
.bar-row{display:grid;grid-template-columns:8.5rem 1fr 3.6rem;gap:.9rem;align-items:center;
  font-family:'Inter',sans-serif;font-size:.7rem;color:var(--ink-soft)}
.bar-track{height:6px;background:var(--paper-dark);border:1px solid var(--line);
  position:relative;overflow:hidden}
.bar-fill{position:absolute;inset:0 auto 0 0;background:var(--vermillion);
  transition:width .45s var(--ease-out)}
.bar-fill.sage{background:var(--sage)}
.bar-val{text-align:right;font-variant-numeric:tabular-nums}

.curve-wrap{border:1px solid var(--line);background:var(--card);padding:1.2rem;margin-top:1.2rem}
.curve-wrap canvas{display:block;width:100%;max-width:520px;height:auto}

.legend{display:flex;flex-wrap:wrap;gap:.3rem 1.4rem;margin-top:1rem;
  font-family:'Inter',sans-serif;font-size:.72rem;color:var(--ink-soft)}
.legend span{display:flex;align-items:center;gap:.45rem}
.sw{width:11px;height:11px;border:1px solid rgba(26,26,26,.2);display:inline-block;flex:none}

.drag-hint{font-family:'Inter',sans-serif;font-size:.66rem;letter-spacing:.1em;
  color:var(--ink-light);margin-top:.7rem;font-style:normal}
canvas.draggable{cursor:grab;touch-action:none}
canvas.draggable:active{cursor:grabbing}

.cmp{display:flex;flex-wrap:wrap;gap:1.6rem;margin-top:1.4rem}
.cmp .imgblock canvas{width:176px;height:176px}
.cmp .imgblock.wide canvas{width:200px;height:200px}
@media(max-width:820px){
  .cmp .imgblock canvas,.cmp .imgblock.wide canvas{width:min(200px,42vw);height:min(200px,42vw)}
  .bar-row{grid-template-columns:6.5rem 1fr 3rem}
}

/* ═════ readouts & cards ═════ */
.readout{font-family:'Inter',sans-serif;font-size:.79rem;color:var(--ink-soft);line-height:2}
.readout b{color:var(--vermillion);font-weight:500}
.bignum{font-family:'Cormorant Garamond',serif;font-size:2.1rem;color:var(--vermillion);line-height:1.3;margin-top:.5rem}
.grid2{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:1.6rem 2rem;margin-top:1.4rem}
.card{background:var(--card);border:1px solid var(--line);padding:1.4rem 1.5rem}

/* ═════ footer ═════ */
.lab-footer{border-top:1px solid var(--line);margin-top:4rem;padding:2.5rem 0 3.5rem;text-align:center}
.lab-footer p{font-family:'Inter',sans-serif;font-size:.72rem;letter-spacing:.12em;color:var(--ink-light);margin:0}
.lab-footer a{color:var(--vermillion);text-decoration:none}
.lab-footer a:hover{text-decoration:underline}

/* ═════ series navigation (prev / next lab) ═════ */
.lab-pager{display:flex;justify-content:space-between;gap:1rem;flex-wrap:wrap;
  border-top:1px solid var(--line);margin-top:3.5rem;padding-top:2rem}
.lab-pager a{text-decoration:none;color:inherit;max-width:44%;transition:color .3s var(--ease-soft)}
.lab-pager a:hover .pager-title{color:var(--vermillion)}
.lab-pager .next{text-align:right;margin-left:auto}
.pager-dir{font-family:'Inter',sans-serif;font-size:.6rem;letter-spacing:.24em;text-transform:uppercase;
  color:var(--ink-light);display:block;margin-bottom:.4rem}
.pager-title{font-family:'Cormorant Garamond',serif;font-size:1.3rem;transition:color .3s var(--ease-soft)}

/* ═════ reveal on scroll ═════ */
.reveal{opacity:0;transform:translateY(22px);
  transition:opacity 1s var(--ease-soft),transform 1s var(--ease-out);will-change:opacity,transform}
.reveal.visible{opacity:1;transform:none;will-change:auto}
.reveal.d1{transition-delay:.08s}
.reveal.d2{transition-delay:.18s}
.reveal.d3{transition-delay:.28s}
.reveal.d4{transition-delay:.38s}

/* ═════ responsive ═════ */
@media(max-width:900px){
  .top-bar{padding:1rem 1.4rem}
  .nav-links{gap:.9rem}
  .nav-links a{font-size:.58rem;letter-spacing:.12em}
}
@media(max-width:640px){.nav-links{display:none}}
@media(max-width:820px){
  .container{padding:0 1.3rem}
  .section-heading-text{font-size:1.6rem}
  .eqmath{font-size:1.1rem}
  .imgblock canvas{width:min(260px,42vw);height:min(260px,42vw)}
  .lab-pager a{max-width:100%}
}

@media(prefers-reduced-motion:reduce){
  *,*::before,*::after{animation-duration:.01ms!important;animation-iteration-count:1!important;
    transition:none!important}
  html{scroll-behavior:auto}
  .reveal{opacity:1;transform:none}
}

/* ═══════════════════════════════════════════════════════════════════
   Image Processing workbench — used with imgproc.js
   ═══════════════════════════════════════════════════════════════════ */

/* image picker: samples, upload, drop hint */
.ip-picker{display:flex;flex-direction:column;gap:.7rem;margin:1.4rem 0 1.6rem}
.ip-own{display:flex;align-items:center;flex-wrap:wrap;gap:.4rem .9rem}
.ip-hint{font-family:'Inter',sans-serif;font-size:.68rem;color:var(--ink-light)}
body.ip-dragging::after{content:"Drop the image to load it";position:fixed;inset:12px;z-index:500;
  display:flex;align-items:center;justify-content:center;pointer-events:none;
  border:2px dashed var(--vermillion);background:rgba(244,237,224,.86);color:var(--vermillion);
  font-family:'Cormorant Garamond',serif;font-size:1.8rem;font-style:italic}

/* stage: image on the left, inspector on the right */
.ip-stage{display:grid;grid-template-columns:minmax(0,1.55fr) minmax(220px,1fr);gap:1.8rem;align-items:start}
.ip-view{display:flex;flex-direction:column;gap:.5rem;min-width:0}
.ip-frame{position:relative;width:100%;border:1px solid var(--line);background:var(--paper-dark);
  overflow:hidden;cursor:crosshair;touch-action:none;user-select:none}
.ip-frame canvas{position:absolute;inset:0;width:100%;height:100%;display:block}
.ip-mark{position:absolute;border:1.5px solid var(--vermillion);box-shadow:0 0 0 1px rgba(244,237,224,.8);
  pointer-events:none;min-width:5px;min-height:5px}
.ip-divider{position:absolute;top:0;bottom:0;width:22px;margin-left:-11px;cursor:ew-resize;z-index:3}
.ip-divider::before{content:"";position:absolute;left:10px;top:0;bottom:0;width:2px;background:var(--paper);
  box-shadow:0 0 0 1px rgba(26,26,26,.25)}
.ip-divider span{position:absolute;top:50%;left:2px;width:18px;height:30px;margin-top:-15px;
  background:var(--paper);border:1px solid rgba(26,26,26,.35)}
.ip-divider span::before{content:"‹ ›";position:absolute;inset:0;display:flex;align-items:center;justify-content:center;
  font-family:'Inter',sans-serif;font-size:.62rem;color:var(--ink-soft);letter-spacing:-.05em}
.ip-tag{position:absolute;top:.5rem;font-family:'Inter',sans-serif;font-size:.56rem;letter-spacing:.2em;
  text-transform:uppercase;background:rgba(244,237,224,.88);color:var(--ink-soft);padding:.2em .6em;pointer-events:none}
.ip-tag.l{left:.5rem}.ip-tag.r{right:.5rem}
.ip-dim{font-family:'Inter',sans-serif;font-size:.68rem;color:var(--ink-light)}

.ip-inspect{border:1px solid var(--line);background:var(--card);padding:1.1rem 1.2rem;min-width:0}
.ip-where{font-family:'Inter',sans-serif;font-size:.78rem;color:var(--ink-soft);margin:0 0 .8rem}
.ip-where b{color:var(--vermillion);font-weight:500}
.ip-hoods{display:flex;flex-wrap:wrap;gap:1rem}
.ip-hood-cap{font-family:'Inter',sans-serif;font-size:.56rem;letter-spacing:.2em;text-transform:uppercase;
  color:var(--ink-light);display:block;margin-bottom:.35rem}
.ip-hood{display:grid;grid-template-columns:repeat(5,30px);grid-auto-rows:26px;gap:2px}
.ip-hood .cell{font-size:.62rem}
.ip-explain{font-family:'Inter',sans-serif;font-size:.78rem;color:var(--ink-soft);margin-top:.9rem;line-height:1.7}
.ip-explain b{color:var(--vermillion);font-weight:500}
.ip-explain i{font-family:'Cormorant Garamond',serif;font-size:1.05rem}

/* charts */
.ip-charts{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:1.4rem 1.8rem;margin-top:1.6rem}
.ip-chart{min-width:0}
.ip-chart canvas{display:block;width:100%}
.ip-chart .cap{font-family:'Inter',sans-serif;font-size:.6rem;letter-spacing:.2em;text-transform:uppercase;
  color:var(--ink-light);display:block;margin-bottom:.4rem}
.ip-chart .cap em{font-style:normal;color:var(--vermillion);text-transform:none;letter-spacing:.04em}
.ip-curve{max-width:320px}
.ip-curve canvas{touch-action:none}

/* try-this challenges */
.ip-tries{border-left:2px solid var(--sage);padding:.3rem 0 .3rem 1.2rem;margin-top:2.2rem}
.ip-tries ol{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:.55rem}
.ip-tries li{display:flex;gap:.75rem;align-items:baseline;color:var(--ink-soft)}
.ip-box{flex:none;width:.85rem;height:.85rem;border:1px solid var(--ink-light);position:relative;top:.1rem}
.ip-tries li.done{color:var(--ink)}
.ip-tries li.done .ip-box{background:var(--sage);border-color:var(--sage)}
.ip-tries li.done .ip-box::after{content:"✓";position:absolute;inset:0;display:flex;align-items:center;
  justify-content:center;color:var(--paper);font-family:'Inter',sans-serif;font-size:.6rem}

/* book references under a section heading */
.ip-ref{font-family:'Inter',sans-serif;font-size:.66rem;letter-spacing:.06em;color:var(--ink-light);margin:-.6rem 0 0}
.ip-ref b{font-weight:500;color:var(--ink-soft)}

@media(max-width:820px){
  .ip-stage{grid-template-columns:1fr}
  .ip-hood{grid-template-columns:repeat(5,minmax(0,30px))}
}