@font-face{font-family:Fraunces;font-style:normal;font-weight:300 800;font-display:swap;src:url(fonts/fraunces-normal-latin.woff2) format("woff2");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,U+2193,U+2212,U+2215,U+FEFF,U+FFFD}
@font-face{font-family:Fraunces;font-style:normal;font-weight:300 800;font-display:swap;src:url(fonts/fraunces-normal-latin-ext.woff2) format("woff2");unicode-range:U+0100-024F,U+0259,U+1E00-1EFF,U+2020,U+20A0-20AB,U+20AD-20CF,U+2113,U+2C60-2C7F,U+A720-A7FF}
@font-face{font-family:"Source Serif 4";font-style:normal;font-weight:300 700;font-display:swap;src:url(fonts/source-serif-4-normal-latin.woff2) format("woff2");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,U+2193,U+2212,U+2215,U+FEFF,U+FFFD}
@font-face{font-family:"Source Serif 4";font-style:normal;font-weight:300 700;font-display:swap;src:url(fonts/source-serif-4-normal-latin-ext.woff2) format("woff2");unicode-range:U+0100-024F,U+0259,U+1E00-1EFF,U+2020,U+20A0-20AB,U+20AD-20CF,U+2113,U+2C60-2C7F,U+A720-A7FF}
@font-face{font-family:"Source Serif 4";font-style:italic;font-weight:300 700;font-display:swap;src:url(fonts/source-serif-4-italic-latin.woff2) format("woff2");unicode-range:U+0000-00FF,U+2000-206F}
@font-face{font-family:"Source Serif 4";font-style:italic;font-weight:300 700;font-display:swap;src:url(fonts/source-serif-4-italic-latin-ext.woff2) format("woff2");unicode-range:U+0100-024F,U+1E00-1EFF}

/* The microscope field stays black in both themes; the paper follows the theme. Gamboge = Perrin's yellow resin. */
:root{
  --field:#050403;--gum:#e8a92a;--gum-2:#ffd27a;--gum-3:#fff2cf;--snow:#f3efe7;--mist:#b9b2a5;--mist-2:#8d867a;
  --card:rgba(10,8,6,.86);--card-line:rgba(255,222,160,.16);
  --paper:#f5efe2;--paper-2:#ebe3d2;--ink:#1e1a14;--ink-2:#463f35;--ink-3:#675f53;--rule:#d8cfbd;--grid:#d9cfba;
  --accent:#8a5a00;--link:#7a4e00;--focus:#1f5fc9;--ok:#2d6a3e;--band:rgba(232,169,42,.28);--trace:#a76c00;--ghost:rgba(70,60,45,.22);
  color-scheme:light;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --paper:#100e0b;--paper-2:#1a1712;--ink:#ece6da;--ink-2:#cfc7b8;--ink-3:#aaa294;--rule:#2f2a22;--grid:#2c271f;
  --accent:#f0b440;--link:#ffcf75;--focus:#8ab4ff;--ok:#8fd19e;--band:rgba(232,169,42,.22);--trace:#ffc65a;--ghost:rgba(255,236,200,.18);color-scheme:dark}}
:root[data-theme="dark"]{
  --paper:#100e0b;--paper-2:#1a1712;--ink:#ece6da;--ink-2:#cfc7b8;--ink-3:#aaa294;--rule:#2f2a22;--grid:#2c271f;
  --accent:#f0b440;--link:#ffcf75;--focus:#8ab4ff;--ok:#8fd19e;--band:rgba(232,169,42,.22);--trace:#ffc65a;--ghost:rgba(255,236,200,.18);color-scheme:dark}

*{box-sizing:border-box}
html{scroll-padding-top:56px;-webkit-text-size-adjust:100%}
body{margin:0;background:var(--field);color:var(--snow);font:400 1.1rem/1.62 "Source Serif 4",Georgia,serif;overflow-x:hidden}
a{color:var(--gum-2);text-underline-offset:.18em}
:focus-visible{outline:3px solid var(--focus);outline-offset:2px}
.skip{position:absolute;left:-999px;top:0;background:var(--paper);color:var(--ink);padding:.5rem 1rem;z-index:40}
.skip:focus{left:8px;top:8px}
h1,h2,h3{font-family:Fraunces,Georgia,serif;font-weight:500;line-height:1.08;letter-spacing:-.012em;text-wrap:balance}
h1{font-size:clamp(2.3rem,6.2vw,4.5rem);margin:.15em 0 .3em;max-width:16ch;font-weight:450}
h2{font-size:clamp(1.6rem,3.4vw,2.4rem);margin:0 0 .55em}
h3{font-size:1.25rem;margin:1.6em 0 .45em}
p{margin:0 0 1em}
[hidden]{display:none!important}

/* ---------- topbar ---------- */
.topbar{position:sticky;top:0;z-index:30;display:flex;align-items:center;gap:.9rem;height:48px;padding:0 16px;background:rgba(5,4,3,.74);backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);border-bottom:1px solid rgba(255,255,255,.07);font:500 .9rem/1 "Source Serif 4",serif;white-space:nowrap;color:var(--mist)}
.topbar a{color:var(--mist);text-decoration:none}
.topbar a:hover,.topbar a[aria-current="true"]{color:var(--snow);text-decoration:underline;text-decoration-color:var(--gum)}
.home{font-weight:700;color:var(--snow)!important;display:inline-flex;align-items:center;gap:.4rem}
.home-bead{color:var(--gum)}
.topnav{display:flex;gap:.9rem;overflow-x:auto;scrollbar-width:none;min-width:0;flex:1 1 auto}
.topnav::-webkit-scrollbar{display:none}
.topnav a{display:inline-flex;align-items:center;min-height:44px}
.lang{font-weight:700;letter-spacing:.04em;min-width:44px;min-height:44px;display:inline-flex;align-items:center;justify-content:center}
.icon-btn{background:none;border:0;color:var(--snow);width:44px;height:44px;display:inline-flex;align-items:center;justify-content:center;cursor:pointer;border-radius:50%;flex:none}
.progress{position:absolute;left:0;right:0;bottom:-1px;height:2px;background:rgba(232,169,42,.14);pointer-events:none}
.progress i{position:absolute;left:0;top:-3px;width:8px;height:8px;margin-left:-4px;border-radius:50%;background:var(--gum-2);box-shadow:0 0 8px rgba(255,210,122,.8);will-change:transform}
@media (max-width:560px){.home{display:none}}

/* ---------- the microscope stage ---------- */
.scene{position:relative}
.stage{position:sticky;top:0;height:100vh;height:100lvh;overflow:hidden;margin-top:-48px;background:var(--field);touch-action:pan-y}
.stage .still,.stage canvas.fill{position:absolute;inset:0;width:100%;height:100%;display:block}
.stage .still{object-fit:cover;filter:sepia(1) saturate(3.2) hue-rotate(-12deg) brightness(.95);opacity:.9}
.stage.live .still{display:none}
.stage canvas.fill{cursor:crosshair}
.steps{position:relative;z-index:2;margin-top:-100vh;margin-top:-100lvh;pointer-events:none}
.step{min-height:100vh;min-height:100svh;display:flex;align-items:center;padding:14vh 16px 12vh;max-width:1240px;margin:0 auto}
.play-room{min-height:85vh;min-height:85svh;padding:0}
.card{pointer-events:auto;width:min(27rem,100%);background:var(--card);border:1px solid var(--card-line);border-radius:14px;padding:1.2rem 1.35rem;color:#ece7dd;backdrop-filter:blur(8px);-webkit-backdrop-filter:blur(8px);box-shadow:0 20px 50px -20px rgba(0,0,0,.85)}
.card h2{font-size:clamp(1.5rem,3vw,2.05rem);color:#fff;margin-bottom:.5rem}
.card p{font-size:1.03rem;line-height:1.56;margin-bottom:.75rem}
.card p:last-child{margin-bottom:0}
.card .note{font-size:.9rem;color:var(--mist)}
.kick{font:600 .78rem/1.2 "Source Serif 4",serif;letter-spacing:.14em;text-transform:uppercase;color:var(--gum);margin:0 0 .55rem}
.hero-step{align-items:flex-end;padding-top:18vh;padding-bottom:10vh}
.hero{pointer-events:none;max-width:46rem}
.hero h1{color:#fff;text-shadow:0 2px 30px #000,0 0 8px rgba(0,0,0,.8)}
.hero .deck{font-size:clamp(1.08rem,2.1vw,1.3rem);line-height:1.5;color:#efe9de;max-width:35rem;text-shadow:0 1px 12px #000,0 0 4px #000}
.hero .kick{text-shadow:0 1px 8px #000}
.cue{font-size:.98rem;color:var(--gum-2);margin:.8rem 0 0;text-shadow:0 1px 8px #000}

/* HUD: the running count */
.hud{position:absolute;top:64px;right:16px;z-index:3;text-align:right;pointer-events:none;color:#fff;max-width:min(22rem,60vw);opacity:0;transform:translateY(-6px);transition:opacity .4s,transform .4s}
.stage.on .hud{opacity:1;transform:none}
.stage.covered .hud,.stage.covered .loupe{opacity:0}
.hud p{margin:0;text-shadow:0 1px 8px #000,0 0 3px #000}
.hud-kick{font:600 .74rem/1.25 "Source Serif 4",serif;letter-spacing:.1em;text-transform:uppercase;color:var(--gum)}
.hud-n{font:500 clamp(2.2rem,5.6vw,3.8rem)/1.02 Fraunces,serif;color:var(--gum-2);letter-spacing:-.02em;font-variant-numeric:tabular-nums;margin:.15rem 0 .1rem!important}
.hud-n.wait{font-size:clamp(1.4rem,3vw,2rem);color:#fff}
.nw{white-space:nowrap}
.hud-n sup{font-size:.48em;vertical-align:.95em;margin-left:.04em}
.hud-range{font-size:.95rem;color:#e8e1d3}
.hud-count{font-size:.95rem;color:var(--mist);margin-top:.35rem!important;font-variant-numeric:tabular-nums}
.hud-one{font-size:.92rem;color:var(--gum-3);margin-top:.2rem!important}
.hud-ref{font-size:.86rem;color:var(--mist);margin-top:.45rem!important}

/* loupe */
.loupe{position:absolute;left:16px;bottom:calc(84px + env(safe-area-inset-bottom));z-index:3;width:200px;height:200px;border-radius:50%;overflow:hidden;border:2px solid var(--gum);box-shadow:0 0 0 4px rgba(0,0,0,.6),0 10px 30px rgba(0,0,0,.6);pointer-events:none;background:#000}
.loupe canvas{width:100%;height:100%;display:block}
.loupe span{position:absolute;right:22px;bottom:18px;font:600 .8rem "Source Serif 4",serif;color:var(--gum-2)}

/* tools */
.tools{position:absolute;left:50%;bottom:calc(18px + env(safe-area-inset-bottom));transform:translateX(-50%);z-index:4;display:flex;gap:.5rem;flex-wrap:nowrap;opacity:0;pointer-events:none;transition:opacity .35s}
.stage.on .tools{opacity:1;pointer-events:auto}
.tool{min-height:44px;padding:.5rem 1rem;border-radius:999px;border:1px solid rgba(255,210,122,.45);background:rgba(10,8,6,.82);color:var(--gum-3);font:600 .95rem/1.1 "Source Serif 4",serif;cursor:pointer;white-space:nowrap;backdrop-filter:blur(6px);-webkit-backdrop-filter:blur(6px)}
.tool:hover{background:rgba(232,169,42,.22)}
.tool.icon{width:44px;padding:0;display:inline-grid;place-items:center}
.toast{position:absolute;left:50%;bottom:calc(76px + env(safe-area-inset-bottom));transform:translateX(-50%);z-index:4;margin:0;max-width:min(30rem,90vw);text-align:center;font-size:.95rem;color:#fff;text-shadow:0 1px 8px #000;pointer-events:none;min-height:1.4em}

/* ---------- paper ---------- */
.paper{background:var(--paper);color:var(--ink);position:relative;z-index:2}
.paper section{padding:3rem 16px;max-width:1180px;margin:0 auto}
.paper a{color:var(--link)}
.prose,.paper section.prose{max-width:41rem;margin-left:auto;margin-right:auto}
.prose.wide,.paper section.prose.wide{max-width:46rem}
.prose h2{color:var(--ink)}
.prose b{font-weight:650}
.formula{margin:1.4rem 0;padding:1rem 1.2rem;border-left:3px solid var(--accent);background:var(--paper-2);border-radius:0 10px 10px 0}
.formula p{margin:0 0 .7rem;font-size:1rem;color:var(--ink-2)}
.formula p:last-child{margin:0}
.formula .eq{display:block;font:500 1.25rem/1.3 Fraunces,serif;color:var(--ink);margin-bottom:.15rem;letter-spacing:.01em}

/* the path without a tangent */
.tangent{margin:1.6rem 0 .5rem}
.tan-ctl{display:flex;flex-wrap:wrap;gap:.4rem;margin:0 0 .9rem}
.tan-ctl button{min-height:44px;padding:.45rem .9rem;border-radius:999px;border:1px solid var(--rule);background:transparent;color:var(--ink-2);font:500 .95rem/1.1 "Source Serif 4",serif;cursor:pointer}
.tan-ctl button[aria-checked="true"]{background:var(--accent);border-color:var(--accent);color:var(--paper)}
html:not(.js) .tan-ctl{display:none}
.tan-plot{max-width:420px;margin:0 auto;border:1px solid var(--rule);border-radius:10px;background:var(--paper-2);padding:6px}
.tan-plot svg{display:block;width:100%;height:auto}
.tan-plot .grid line{stroke:var(--grid);stroke-width:1}
.tan-plot .ghost{fill:none;stroke:var(--ghost);stroke-width:.8;stroke-linejoin:round}
.tan-plot .trace{fill:none;stroke:var(--trace);stroke-width:1.6;stroke-linejoin:round}
.tan-plot #tan-dots circle{fill:var(--trace)}
.tan-plot .start{fill:none;stroke:var(--ink);stroke-width:1.6}
.tan-plot .end{fill:var(--ink)}
.tan-plot .scalebar line{stroke:var(--ink);stroke-width:2.5}
.tan-plot .scalebar text{font:600 12px "Source Serif 4",serif;fill:var(--ink)}
.tan-out{text-align:center;margin:.8rem 0 .4rem;font-size:1.05rem;font-variant-numeric:tabular-nums}
.tan-out b{color:var(--accent)}
figcaption{font-size:.93rem;color:var(--ink-3);line-height:1.5}

/* Perrin's 13 */
.methods{margin:1.4rem 0 1rem}
.methods svg{display:block;width:100%;height:auto}
.methods .band{fill:var(--band)}
.methods .ax{stroke:var(--rule)}
.methods .tick{font:500 12px "Source Serif 4",serif;fill:var(--ink-3)}
.methods .today{stroke:var(--ink);stroke-width:1.5}
.methods .today-t{font:600 12px "Source Serif 4",serif;fill:var(--ink)}
.methods .lab{font:500 12.5px "Source Serif 4",serif;fill:var(--ink-2)}
.methods .m{fill:var(--ink-3)}
.methods .m.brown{fill:var(--accent)}

.glass-out{font:500 1.18rem/1.45 Fraunces,serif;color:var(--ink);padding:.9rem 1.1rem;border:1px solid var(--rule);border-radius:12px;background:var(--paper-2)}
.glass-out b{color:var(--accent);font-weight:600}
.method{font-size:1rem;color:var(--ink-2)}
.sources li{margin:.3rem 0 .6rem;font-size:.96rem;overflow-wrap:anywhere}
.more{list-style:none;padding:0}
.more li{margin:.45rem 0}

/* share, footer, to-top */
.share{padding:1.2rem 16px 2rem!important}
.share-row{display:flex;flex-wrap:nowrap;gap:.35rem;align-items:center}
.share-row .lab{font-size:.95rem;color:var(--ink-3);margin-right:.2rem}
.share-row a,.share-row button{display:inline-grid;place-items:center;flex:none;width:2.5rem;height:2.5rem;padding:0;border-radius:50%;border:1px solid var(--rule);background:transparent;color:var(--ink-2);text-decoration:none;cursor:pointer}
.share-row a:hover,.share-row button:hover,.share-row a:focus-visible,.share-row button:focus-visible{color:var(--accent);border-color:var(--accent)}
@media (pointer:coarse){.share-row a,.share-row button{width:2.75rem;height:2.75rem}}
.share-status{font-size:.95rem;color:var(--ok);min-height:1.2em;margin:.4rem 0 0}
.share-field{width:100%;margin-top:.5rem;padding:.6rem;border:1px solid var(--rule);border-radius:.5rem;background:var(--paper-2);color:var(--ink);font:inherit;font-size:.9rem}
.foot{background:var(--paper);position:relative;z-index:2;border-top:1px solid var(--rule);padding:1.5rem 16px 5rem;text-align:center;color:var(--ink-2);font-size:.95rem}
.foot a{color:var(--link)}
.to-top{position:fixed;right:16px;bottom:calc(16px + env(safe-area-inset-bottom));z-index:25;min-width:48px;height:48px;border-radius:999px;border:1px solid rgba(255,222,160,.35);background:#16120c;color:#f6f1e6;display:inline-flex;align-items:center;gap:.3rem;padding:0 .9rem;font:600 .9rem "Source Serif 4",serif;cursor:pointer;box-shadow:0 4px 14px rgba(0,0,0,.35)}
section[id],.step[id],h3[id]{scroll-margin-top:56px}

/* ---------- phones ---------- */
@media (max-width:760px){
  .step{padding:10vh 12px 6vh}
  .hero-step{padding-bottom:5vh}
  #proba{align-items:flex-end;padding-bottom:calc(120px + env(safe-area-inset-bottom))}
  .card{width:100%;padding:1rem 1.05rem}
  .card p{font-size:1rem}
  .hud{top:56px;right:12px;max-width:62vw}
  .hud-ref{display:none}
  .loupe{left:12px;top:58px;bottom:auto;width:118px;height:118px}
  .tools{gap:.35rem;bottom:calc(12px + env(safe-area-inset-bottom));flex-wrap:wrap;justify-content:center;width:calc(100% - 24px)}
  .tool{padding:.45rem .75rem;font-size:.88rem}
  .toast{bottom:calc(118px + env(safe-area-inset-bottom))}
  .methods .lab{font-size:15px}
}
@media (max-height:640px){.hud-range,.hud-one{display:none}}
@media (prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important;animation:none!important}}
@media print{.topbar,.stage,.to-top,.share{display:none}.steps{margin-top:0}.card{background:none;color:#000;border:0}}