@font-face{font-family:"Literata";src:url(fonts/literata-latin.woff2) format("woff2");font-weight:200 900;font-display:swap;unicode-range:U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+2000-206F,U+2074,U+20AC,U+2122,U+2191-2199,U+2212,U+2215,U+FEFF,U+FFFD}
@font-face{font-family:"Literata";src:url(fonts/literata-latin-ext.woff2) format("woff2");font-weight:200 900;font-display:swap;unicode-range:U+0100-02AF,U+0304,U+0308,U+0329,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF}
@font-face{font-family:"Plex";src:url(fonts/ibmplexsans-400-lat.woff2) format("woff2");font-weight:400;font-display:swap;unicode-range:U+0000-00FF,U+2000-206F,U+2190-2199,U+2212}
@font-face{font-family:"Plex";src:url(fonts/ibmplexsans-400-ext.woff2) format("woff2");font-weight:400;font-display:swap;unicode-range:U+0100-02AF,U+1E00-1EFF}
@font-face{font-family:"Plex";src:url(fonts/ibmplexsans-600-lat.woff2) format("woff2");font-weight:600;font-display:swap;unicode-range:U+0000-00FF,U+2000-206F,U+2190-2199,U+2212}
@font-face{font-family:"Plex";src:url(fonts/ibmplexsans-600-ext.woff2) format("woff2");font-weight:600;font-display:swap;unicode-range:U+0100-02AF,U+1E00-1EFF}

:root{
  --bg:#f4ecda;--paper:#faf6ea;--ink:#2b2113;--mut:#65582f;--line:#d3c5a0;
  --clay:#7c4300;--gold:#6e4e00;--gold-soft:#a8842c;--focus:#6e4e00;--bar:rgba(244,236,218,.92);
  --disk:#181410;
  --serif:"Literata",Georgia,serif;--sans:"Plex",system-ui,-apple-system,"Segoe UI",sans-serif;
  color-scheme:light;
}
:root[data-theme="dark"]{
  --bg:#16110a;--paper:#211a11;--ink:#f2e8d5;--mut:#b3a586;--line:#3d3322;
  --clay:#e8a83e;--gold:#e8b64c;--gold-soft:#8f7434;--focus:#ffd98a;--bar:rgba(22,17,10,.92);
  --disk:#181410;
  color-scheme:dark;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --bg:#16110a;--paper:#211a11;--ink:#f2e8d5;--mut:#b3a586;--line:#3d3322;
  --clay:#e8a83e;--gold:#e8b64c;--gold-soft:#8f7434;--focus:#ffd98a;--bar:rgba(22,17,10,.92);
  --disk:#181410;
  color-scheme:dark;
}}

*{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
body{margin:0;background:var(--bg);color:var(--ink);font:400 1.08rem/1.62 var(--serif);font-optical-sizing:auto;overflow-x:clip}
[hidden]{display:none !important}
a{color:var(--clay);text-underline-offset:.15em}
a:focus-visible,button:focus-visible,select:focus-visible,summary:focus-visible,input:focus-visible{outline:3px solid var(--focus);outline-offset:2px;border-radius:4px}
h1,h2,h3{font-family:var(--serif);line-height:1.12;margin:0 0 .5em}
h2{font-size:clamp(1.9rem,4.2vw,3rem);font-weight:600;letter-spacing:-.01em}
h2 .anchor{color:inherit;text-decoration:none}
h3{font-size:1.2rem;font-weight:650}
p{margin:0 0 1em}
.skip{position:absolute;left:-999px;top:0}.skip:focus{left:8px;top:8px;z-index:60;background:var(--paper);padding:.4em .8em}
section{scroll-margin-top:52px;padding:clamp(3rem,8vw,6rem) clamp(16px,5vw,64px);max-width:1280px;margin:0 auto}
.lede{font-size:1.18rem;max-width:40em;color:var(--ink)}
figcaption{font:400 .82rem/1.45 var(--sans);color:var(--mut);margin-top:.55em}
figure{margin:0}
.note{font:400 .88rem/1.5 var(--sans);color:var(--mut);margin-top:1.6rem}
img{height:auto}

/* topbar */
.topbar{position:sticky;top:0;z-index:30;display:flex;align-items:center;gap:.9rem;height:46px;padding:0 clamp(12px,3vw,28px);background:var(--bar);backdrop-filter:blur(8px);-webkit-backdrop-filter:blur(8px);border-bottom:1px solid var(--line);font:400 .9rem/1 var(--sans);white-space:nowrap}
.topbar a{color:var(--ink);text-decoration:none}
.home{font-weight:600}
.topnav{display:flex;gap:1rem;overflow-x:auto;scrollbar-width:none;min-width:0}
.topnav::-webkit-scrollbar{display:none}
.topnav a{color:var(--mut);padding:.35em 0}
.topnav a[aria-current="true"]{color:var(--ink);box-shadow:inset 0 -2px var(--gold)}
.spacer{flex:1}
.chip{border:1px solid var(--line);border-radius:999px;padding:.35em .8em}
.icon-btn{width:34px;height:34px;border-radius:50%;border:1px solid var(--line);background:transparent;color:var(--ink);display:grid;place-items:center;cursor:pointer;padding:0;flex:none}
.icon-btn svg{display:block}.icon-btn svg[hidden]{display:none}
@media (max-width:560px){.home{display:none}.topnav{gap:.8rem}}

/* progress hairline + reading rail */
.progress{position:fixed;top:0;left:0;right:0;height:3px;z-index:40;pointer-events:none}
.progress .hair{position:absolute;inset:0;background:var(--gold);transform:scaleX(0);transform-origin:0 50%}
.progress .bee{position:absolute;top:-3.5px;width:10px;height:10px;margin-left:-5px;border-radius:50%;background:var(--gold);box-shadow:0 0 0 2px var(--bg)}
.rail{position:fixed;right:14px;top:50%;transform:translateY(-50%);z-index:29;display:flex;flex-direction:column;gap:.55rem}
.rail a{position:relative;width:26px;height:26px;display:grid;place-items:center;text-decoration:none}
.rail a i{width:9px;height:9px;border-radius:50%;background:transparent;border:2px solid var(--mut);display:block}
.rail a[aria-current="true"] i{background:var(--gold);border-color:var(--gold)}
.rail a::after{content:attr(aria-label);position:absolute;right:30px;top:50%;transform:translateY(-50%);font:400 .78rem var(--sans);color:var(--ink);background:var(--paper);border:1px solid var(--line);border-radius:6px;padding:.25em .7em;white-space:nowrap;opacity:0;pointer-events:none}
.rail a:hover::after,.rail a:focus-visible::after{opacity:1}
@media (max-width:79.99rem){.rail{display:none}}

/* hero */
.hero{display:grid;grid-template-columns:1fr 1fr;gap:clamp(1.5rem,5vw,4rem);align-items:center;min-height:calc(100svh - 46px);padding-top:clamp(1.5rem,4vw,3rem)}
.kicker{font:600 .8rem/1.3 var(--sans);letter-spacing:.12em;text-transform:uppercase;color:var(--gold);margin-bottom:1.1em}
h1{font-size:clamp(2.7rem,7vw,5.6rem);font-weight:700;letter-spacing:-.025em;line-height:.98;margin-bottom:.35em}
.deck{font-size:clamp(1.12rem,1.9vw,1.4rem);line-height:1.5;max-width:31em}
.cta{display:flex;flex-wrap:wrap;gap:.7rem;margin-top:1.2em}
.start{display:inline-flex;align-items:center;gap:.5em;font:600 1rem/1 var(--sans);color:#fff;background:#5c4300;text-decoration:none;padding:.85em 1.25em;border-radius:999px;min-height:44px;border:0;cursor:pointer}
:root[data-theme="dark"] .start{background:var(--gold);color:#16110a}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]) .start{background:var(--gold);color:#16110a}}
.ghost{display:inline-flex;align-items:center;font:600 1rem/1 var(--sans);color:var(--ink);background:transparent;border:1.5px solid var(--line);border-radius:999px;padding:.85em 1.25em;min-height:44px;text-decoration:none;cursor:pointer}
.hero-fig canvas{width:min(100%,calc(72svh));height:auto;border-radius:12px;margin:0 auto;display:block;background:var(--disk)}
.hero-src{font:400 .82rem var(--sans);color:var(--mut);margin-top:.9em}
@media (max-width:820px){.hero{grid-template-columns:1fr;min-height:0}.hero-fig canvas{width:min(100%,calc(44svh))}}

/* share */
.share{display:flex;align-items:center;flex-wrap:wrap;gap:.6rem 1rem;padding-top:0;padding-bottom:0}
.share-label{font:400 .85rem var(--sans);color:var(--mut)}
.share-row{display:flex;gap:.5rem}
.sh{width:40px;height:40px;border-radius:50%;border:1px solid var(--line);background:transparent;color:var(--ink);display:grid;place-items:center;cursor:pointer;padding:0;text-decoration:none}
.sh:hover,.sh:focus-visible{border-color:var(--gold);color:var(--gold)}
@media (pointer:coarse){.sh{width:44px;height:44px}}
.copy-note{font:400 .85rem var(--sans);color:var(--mut);min-height:1.2em}

/* look */
.photofig{margin:1.6rem 0 .5rem}
.photofig img{display:block;width:min(100%,560px);height:auto;border-radius:10px}
.cgrid{display:grid;grid-template-columns:repeat(auto-fit,minmax(270px,1fr));gap:1.2rem;margin-top:1.6rem}
.cause{background:var(--paper);border:1px solid var(--line);border-radius:10px;padding:1.3rem 1.4rem}
.cause p{max-width:34em;margin-bottom:0}

/* knob: scrolly steps driving the sticky sim */
.recipe{display:flex;flex-wrap:wrap;gap:.6rem 1rem;align-items:baseline;margin:1.4rem 0 2rem;font:400 1rem var(--sans)}
.recipe code{font:600 1.25rem var(--serif);background:var(--paper);border:1px solid var(--line);border-radius:8px;padding:.3em .7em;font-variant-numeric:tabular-nums}
.recipe span{color:var(--mut)}
.journey-cols{display:grid;grid-template-columns:7fr 5fr;gap:clamp(1.5rem,4vw,3rem);align-items:start}
.map-wrap{position:sticky;top:56px}
.simfig canvas{display:block;width:100%;height:auto;border-radius:12px;background:var(--disk)}
.simread{font:600 1.25rem var(--serif);font-variant-numeric:tabular-nums;color:var(--ink);margin-top:.6em;min-height:1.4em}
.steps{display:grid;gap:1.2rem}
.step{background:var(--paper);border:1px solid var(--line);border-radius:10px;padding:1.2rem 1.3rem 1rem;scroll-margin-top:70px}
.step.on{border-color:var(--gold);box-shadow:0 0 0 1px var(--gold)}
@media (min-width:821px){.step{opacity:.55}.step.on{opacity:1}}
.wk{font:600 .8rem/1.4 var(--sans);letter-spacing:.06em;text-transform:uppercase;color:var(--gold);margin-bottom:.6em;font-variant-numeric:tabular-nums}
.stepbtns{display:flex;flex-wrap:wrap;gap:.6rem;margin:.9em 0 0}
.stepbtns .ghost{font-size:.9rem;padding:.6em 1em;min-height:44px}
.statics{display:grid;gap:1.6rem;margin-top:1.6rem}
.statics img{width:min(100%,560px);border-radius:10px}

/* free simulator */
.simfree{display:grid;grid-template-columns:1.1fr 1fr;gap:clamp(1.5rem,4vw,3rem);align-items:start;margin-top:1.6rem}
.simfree .simfig canvas{width:min(100%,62svh);margin:0 auto}
.controls{font:400 1rem var(--sans)}
.crow{display:flex;flex-wrap:wrap;gap:.6rem .8rem;align-items:center;margin:0 0 1.1em}
.crow label,.crow #famlabel{font-weight:600}
input[type="range"]{accent-color:var(--gold);width:min(100%,20em);min-height:44px}
output{font-variant-numeric:tabular-nums;font-weight:600;min-width:6.2em}
.presets{display:flex;flex-wrap:wrap}
.pbtn,.fbtn{font:400 .95rem var(--sans);color:var(--ink);background:var(--paper);border:1.5px solid var(--line);border-radius:999px;padding:.55em 1em;min-height:44px;cursor:pointer;font-variant-numeric:tabular-nums}
.pbtn:hover,.fbtn:hover{border-color:var(--gold)}
.fbtn.on{background:var(--gold);border-color:var(--gold);color:#fff}
:root[data-theme="dark"] .fbtn.on{color:#16110a}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]) .fbtn.on{color:#16110a}}
.fams{display:inline-flex;flex-wrap:wrap;gap:.5rem}
.famline{font-size:1.05rem;min-height:1.5em}
.exact{background:var(--paper);border:1px solid var(--line);border-radius:10px;padding:1.2rem 1.3rem;margin-top:1.8rem;max-width:44em}

/* photo exercise */
.photo .photofig img{width:min(100%,369px)}
#reveal .photofig img{width:min(100%,738px)}
.countform{margin-top:1.4rem;font:400 1rem var(--sans)}
.countform input{font:400 1.1rem var(--sans);color:var(--ink);background:var(--paper);border:1.5px solid var(--line);border-radius:8px;padding:.6em .8em;min-height:44px;width:6em;font-variant-numeric:tabular-nums}
.phint{color:var(--mut);max-width:36em}
.verdict{font-size:1.25rem;max-width:36em;font-weight:500;border-left:4px solid var(--gold);padding-left:1rem;margin-top:1.4rem}

/* reversal chart (inline SVG, no inline styles) */
.chart{display:block;width:min(100%,640px);height:auto;margin:1.2rem 0 1.6rem}
.chart text{font:400 15px var(--serif);fill:var(--ink)}
.chart .bn{font-weight:600;font-variant-numeric:tabular-nums}
.chart .btrack{fill:var(--paper);stroke:var(--line)}
.chart .bfill.fib{fill:var(--gold)}
.chart .bfill.non{fill:var(--clay)}
.rev p,.drops p,.ro p{max-width:40em}
.chips{list-style:none;padding:0;margin:0 0 1.6rem;display:flex;flex-wrap:wrap;gap:.7rem}
.chips li{font:400 .95rem var(--sans);background:var(--paper);border:1px solid var(--line);border-radius:999px;padding:.6em 1.1em}
.chips strong{font-variant-numeric:tabular-nums}
.ro-end{font-size:1.15rem;border-left:4px solid var(--gold);padding-left:1rem;max-width:36em}

/* quiz */
.qlist{display:grid;gap:1.2rem;margin-top:1.4rem}
.q{background:var(--paper);border:1px solid var(--line);border-radius:10px;padding:1.2rem 1.3rem;scroll-margin-top:70px}
.qq{font-size:1.1rem;font-weight:600}
.qn{display:inline-grid;place-items:center;width:1.7em;height:1.7em;border-radius:50%;background:var(--gold);color:#fff;font:600 .85rem var(--sans);margin-right:.5em}
:root[data-theme="dark"] .qn{color:#16110a}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]) .qn{color:#16110a}}
.opts{list-style:none;padding:0;margin:.8em 0 0;display:grid;gap:.5rem}
.opt{font:400 1rem var(--sans);color:var(--ink);background:transparent;border:1.5px solid var(--line);border-radius:8px;padding:.7em 1em;min-height:44px;cursor:pointer;text-align:left;width:100%}
.opt.picked{border-color:var(--gold)}
.opt.right{border-color:#2e7d43;background:rgba(46,125,67,.12)}
.opt.wrong{border-color:#b3261e;background:rgba(179,38,30,.10)}
.qfb{font:400 .92rem var(--sans);margin:.7em 0 0}
.score{font:600 1.2rem var(--serif);min-height:1.6em}
.qkey{font:400 .95rem var(--sans);color:var(--mut)}

/* faq */
.qalist{display:grid;gap:.7rem;margin-top:1.4rem;max-width:44em}
.qa{background:var(--paper);border:1px solid var(--line);border-radius:10px;padding:1rem 1.2rem}
.qa summary{cursor:pointer;font-weight:600;font-size:1.05rem;min-height:44px;display:flex;align-items:center}
.qa p{margin:.6em 0 0}

/* method + sources + footer */
.method p,.src p{max-width:52em}
.src{font:400 .95rem/1.6 var(--sans);color:var(--mut)}
.src h2,.src h3{color:var(--ink)}
.sgroup{margin-bottom:1.4rem}
.sgroup ul{padding-left:1.2em;margin:.4em 0}
.sgroup li{margin-bottom:.3em}
.src a,.method p{overflow-wrap:anywhere}
.foot{padding:2rem clamp(16px,5vw,64px) 3rem;font:400 .85rem var(--sans);color:var(--mut);border-top:1px solid var(--line);max-width:1280px;margin:0 auto}
.foot a{color:var(--mut)}
.nf main{max-width:40em;margin:20vh auto;padding:0 16px}

/* no-JS: everything readable, dead controls hidden */
html:not(.has-js) canvas{display:none}
html:not(.has-js) .step{opacity:1}
html:not(.has-js) #controls,html:not(.has-js) .stepbtns,html:not(.has-js) #showanswer{display:none}
html:not(.has-js) #countform{display:none}

@media (max-width:820px){
  .journey-cols,.simfree{grid-template-columns:1fr}
  .map-wrap{top:46px}
  .map-wrap .simfig canvas{width:min(100%,30svh)}
  .map-wrap .simread{font-size:1.05rem;min-height:1.2em}
  .step{position:relative;z-index:2;scroll-margin-top:calc(46px + 30svh + 64px)}
}
@media (min-width:821px) and (max-width:1180px){.journey-cols{grid-template-columns:1fr 1fr}}
@media (max-width:560px){
  section{scroll-margin-top:60px}
  .chart text{font-size:13px}
}
@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{transition:none !important;animation:none !important}
}