:root{--split:minmax(0, 1.3fr) minmax(0, 1fr);--split-gap:72px;--row-meta:16rem;--paper:#faedf0;--paper-dark:#f2dbe1;--ink:#151515;--muted:#6f5b61;--line:#e4c8cf;--line-strong:#c9a0ab;--control-edge:#a3737f;--danger:#b42318;--danger-tint:#fdecea;--paper-hover:#fff7f9;--brand:#0369a1;--brand-dark:#075985;--tint:#e0f2fe;--studio:#0b0f1a;--accent:#7fe3ff;--font:"Archivo", system-ui, sans-serif;--mono:"DM Mono", ui-monospace, Menlo, monospace;--fs-2xs:11px;--fs-xs:12px;--fs-sm:14px;--fs-md:16px;--fs-lg:18px;--fs-xl:22px;--fs-2xl:28px;--fs-3xl:36px;--fs-section:clamp(24px, 2.7vw, 32px);--fs-feature:clamp(30px, 3.5vw, 46px);--fs-display-compact:clamp(44px, 5.4vw, 76px);--fs-display:clamp(64px, 6.7vw, 92px);--fs-display-home:clamp(48px, 6.3vw, 88px);--fs-display-phone:clamp(40px, 12vw, 72px);--fs-diagram-tick:9.5px;--fs-diagram-label:10px;--fs-diagram-caption:18px;--lh-display:1.02;--lh-heading:1.15;--lh-ui:1.5;--lh-body:1.7;--lh-prose:1.9;--track-caps:.1em;--track-label:.04em;--track-title:-.03em;--track-heading:-.04em;--track-display:-.06em;--track-figure:-.04em;--radius-sm:4px;--radius:6px;--radius-lg:10px;--radius-pill:999px;color-scheme:light;scrollbar-gutter:stable both-edges;scroll-behavior:smooth;scroll-padding-top:28px}*{box-sizing:border-box}html{background:var(--paper)}body{font-family:var(--font);color:var(--ink);background:var(--paper);-webkit-font-smoothing:antialiased;margin:0}a{color:var(--brand);font-weight:600;text-decoration:none}a:hover{text-decoration:underline}:is(h1,h2,h3,h4){font-weight:800;line-height:var(--lh-heading)}:is(h1,h2,h3,h4) a{font-weight:inherit}button{cursor:pointer;font-family:inherit}:focus-visible{outline:3px solid var(--brand);outline-offset:5px}.ltr{direction:ltr;unicode-bidi:isolate}.visually-hidden{clip-path:inset(50%);white-space:nowrap;border:0;width:1px;height:1px;margin:-1px;padding:0;position:absolute;overflow:hidden}.math math{font-family:var(--font), math}.math mi{text-transform:none}.math mi.mi-v{font-style:italic}.skip-link{inset-inline-start:18px;z-index:20;height:34px;font-size:var(--fs-xs);color:#fff;background:var(--brand);border:1.5px solid var(--brand-dark);border-radius:var(--radius);box-shadow:0 2px 0 var(--brand-dark);align-items:center;padding:0 14px;font-weight:700;display:inline-flex;position:fixed;top:12px;transform:translateY(-200%)}.skip-link:not(:focus){clip-path:inset(50%);opacity:0;pointer-events:none}.skip-link:focus{text-decoration:none;transform:none}.topbar{--gutter:44px;max-width:1320px;padding:24px var(--gutter);justify-content:space-between;align-items:center;gap:12px;margin:auto;display:flex;position:relative}.topbar:after{content:"";inset-inline:var(--gutter);border-bottom:1.5px solid var(--line);position:absolute;bottom:0}.site-footer{max-width:1320px;margin:auto;padding:0 44px}.wordmark{font-size:var(--fs-xl);letter-spacing:var(--track-display);color:var(--ink);align-items:center;font-weight:800;display:inline-flex}.wordmark:hover{text-decoration:none}.wordmark{position:relative}.wordmark:after{content:"";inset-inline:-4px;position:absolute;top:calc(50% - 22px);bottom:calc(50% - 22px)}.wordmark b{color:var(--brand)}.wordmark svg{fill:none;width:29px;height:29px;stroke:var(--brand);stroke-width:1.8px;stroke-linejoin:round;margin-inline-end:10px}.topbar nav{font-size:var(--fs-sm);align-items:center;gap:36px;display:flex}.topbar nav a{white-space:nowrap;align-items:center;gap:4px;min-height:44px;margin-block:-12px;font-weight:600;display:inline-flex}.topbar .lang-switch{border-inline-start:1.5px solid var(--line-strong);min-height:24px;margin-block:0;margin-inline-start:-16px;padding-inline-start:20px;position:relative}.topbar .lang-switch:before{content:"";position:absolute;inset:-10px 0}.topbar .nav-short{display:none}.site-tagline{color:var(--muted);font-size:var(--fs-xs)}.scene-viewport{background:var(--studio);color:#eef2fa;min-width:0;min-height:540px;position:relative;overflow:hidden}.stage__canvas{position:absolute;inset:0}.stage__canvas canvas{display:block}.stage__canvas:focus-visible{outline:none}.stage__canvas:focus-visible:after{content:"";z-index:3;border:3px solid var(--accent);border-radius:var(--radius);pointer-events:none;position:absolute;inset:4px}.stage__overlay{z-index:1;pointer-events:none;position:absolute;inset:0;overflow:hidden}.scene-topline,.scene-bottomline{z-index:2;font-size:var(--fs-2xs);color:#a5b0c8;pointer-events:none;justify-content:space-between;align-items:center;gap:12px;display:flex;position:absolute;inset-inline:24px}.scene-topline{font-family:var(--mono);top:18px}.scene-topline>span:not(:empty),.scene-bottomline>span:not(:empty){border-radius:var(--radius-sm);line-height:var(--lh-ui);background:#1d1f27d9;border:1px solid #46536b;padding:4px 8px}.scene-live{text-transform:uppercase;letter-spacing:var(--track-caps)}.scene-live:before{content:"";background:var(--accent);border-radius:50%;width:5px;height:5px;margin-inline-end:8px;display:inline-block}.scene-bottomline{bottom:20px}.scene-bottomline>span{min-width:0}.scene-hint--short{display:none}@media (width<=639px){.scene-hint--long{display:none}.scene-hint--short{display:inline}.scene-live{display:none}.scene-topline>span:not(:empty){white-space:nowrap;text-overflow:ellipsis;min-width:0;overflow:hidden}}.scene-bottomline button{white-space:nowrap;pointer-events:auto;color:#dce5f5;border-radius:var(--radius);height:34px;font-size:var(--fs-xs);background:#101626;border:1px solid #3d475b;flex:none;padding:0 11px;font-weight:600}.scene-bottomline button:hover{background:#1a2440}.scene-error{color:#e8eaf0;font-size:var(--fs-sm);line-height:var(--lh-body);text-align:center;place-items:center;padding:24px;display:grid;position:absolute;inset:0}.scene-error--lost{z-index:2;background:var(--studio)}.scene-error p{margin:0}.scene-poster{object-fit:cover;width:100%;height:100%;position:absolute;inset:0}.scene-error.has-poster{align-items:end;padding-bottom:70px}.scene-error.has-poster p{border-radius:var(--radius);max-width:440px;font-size:var(--fs-xs);background:#101626e6;border:1px solid #3d475b;padding:10px 14px;position:relative}.callout{border-radius:var(--radius);color:#e8eaf0;max-width:calc(100% - 24px);font-size:var(--fs-2xs);font-weight:500;line-height:var(--lh-ui);text-align:center;opacity:0;will-change:transform;background:#1d1f27;border:1px solid #46536b;align-items:center;gap:8px;padding:8px 10px;display:inline-flex;position:absolute;top:0;left:0;transform:translate(-50%,-50%)}.callout:before{content:"";background:var(--accent);border-radius:50%;flex:none;width:5px;height:5px}.callout--pinned{text-align:start;justify-content:start;width:calc(100% - 32px)}.scene-charts{min-width:0;color:var(--ink);background:#fff;flex-direction:column;gap:16px;padding:20px;display:flex}.scene-charts--held{position:relative}.scene-charts--held>.scene-chart{visibility:hidden}.scene-charts__held{top:20px;border:1.5px dashed var(--line);border-radius:var(--radius);color:var(--muted);font-size:var(--fs-sm);line-height:var(--lh-body);margin:0;padding:14px 16px;position:absolute;inset-inline:20px}.scene-notes{min-width:0;color:var(--ink);background:#fff;padding:16px 20px 20px}.scene-notes>.article-kicker{color:var(--muted);font-size:var(--fs-2xs);display:block}.scene-notes__cell{display:grid}.scene-notes__cell>*{grid-area:1/1}.scene-notes .is-spare{visibility:hidden}.scene-notes p{font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--muted);margin:6px 0 0}.scene-notes__cell.is-strong p{font-size:var(--fs-md);font-weight:800;line-height:var(--lh-heading);color:var(--ink);margin-top:8px}.scene-notes__callouts{margin:0;padding:0;list-style:none}.scene-notes__callouts p{color:var(--ink);gap:8px;font-weight:600;display:flex}.scene-notes__callouts p:before{content:"";background:var(--accent);border-radius:50%;flex:none;width:6px;height:6px;margin-top:.6em}.scene-chart{min-width:0;max-width:440px}.scene-chart+.scene-chart{border-top:1.5px solid var(--line);padding-top:16px}.scene-chart__kicker{font-size:var(--fs-2xs);letter-spacing:var(--track-caps);text-transform:uppercase;color:var(--brand);margin:0 0 5px;font-weight:800}.scene-chart__title{font-size:var(--fs-lg);font-weight:800;line-height:var(--lh-heading);letter-spacing:var(--track-title);margin:0 0 8px}.scene-chart svg{width:100%;height:auto;font-family:var(--font);display:block;overflow:visible}.scene-chart__foot{font-size:var(--fs-xs);line-height:var(--lh-ui);color:var(--muted);margin-top:8px}.scene-chart__foot b{color:var(--ink);font-weight:700}.chart-stack{display:grid}.chart-stack>*{grid-area:1/1}.chart-stack>.is-spare{visibility:hidden}.scene-chart__key{flex-wrap:wrap;gap:4px 14px;margin-bottom:3px;display:flex}.scene-chart__key i{border-radius:var(--radius-sm);vertical-align:middle;width:14px;height:4px;margin-inline-end:6px;display:inline-block}.scene-chart__image{border-radius:var(--radius-sm);width:100%;height:auto;display:block}.scene-readings{border-top:1.5px solid var(--line);margin:0}.scene-readings div{border-bottom:1px solid var(--line);font-size:var(--fs-xs);line-height:var(--lh-ui);justify-content:space-between;align-items:baseline;gap:12px;padding:7px 0;display:flex}.scene-readings dt{color:var(--muted)}.scene-readings dd{font-family:var(--mono);color:var(--ink);text-align:end;unicode-bidi:plaintext;margin:0;font-weight:500}.scene-readings dd.is-brand{color:var(--brand)}.scene-readings dd.is-amber{color:#b45309}.scene-readings dd.is-muted{color:var(--muted)}.scene-readings+svg,.scene-readings+.scene-chart__image{margin-top:12px}.sc-axis{fill:none;stroke:var(--ink);stroke-width:1.5px}.sc-grid{fill:none;stroke:var(--line);stroke-width:1px}.sc-tick{fill:var(--muted);font-size:var(--fs-diagram-tick);font-weight:600}.sc-label{fill:var(--ink);font-size:var(--fs-diagram-label);font-weight:700}.hud-panel{color:var(--ink);background:#fff;flex-direction:column;gap:22px;padding:23px;display:flex}.hud-panel h3{font-size:var(--fs-xl);font-weight:800;line-height:var(--lh-heading);letter-spacing:var(--track-heading);margin:-9px 0 0}.lab-controls-heading{justify-content:space-between;align-items:center;gap:12px;display:flex}.lab-controls-heading .article-kicker{font-size:var(--fs-2xs);color:var(--muted);margin:0}.reset-scene{height:34px;color:var(--muted);font-size:var(--fs-xs);border-radius:var(--radius);background:0 0;border:0;padding:0 8px;font-weight:700}.reset-scene:hover{background:var(--paper-dark)}.control{gap:8px;display:grid}.control-row{flex-wrap:wrap;gap:22px 16px;display:flex}.control-row>.control{flex:auto;grid-template-rows:1fr auto}.control-row>.control>.hud-label{contain:inline-size;align-self:end}.control__head{justify-content:space-between;align-items:baseline;gap:8px;display:flex}.hud-label{font-size:var(--fs-xs);color:var(--ink);font-weight:700;display:block}.control__value{font-family:var(--mono);font-variant-numeric:tabular-nums;color:var(--brand);font-size:var(--fs-lg);letter-spacing:var(--track-figure);flex-shrink:0;justify-items:end;font-weight:500;display:grid}.control__ends{color:var(--muted);font-size:var(--fs-xs);justify-content:space-between;display:flex}.control__ends .is-on{color:var(--brand);font-weight:700}input[type=range]{-webkit-appearance:none;appearance:none;cursor:pointer;background:0 0;outline:none;width:100%;height:44px;margin:-7.5px 0 -15.5px;display:block;position:relative}input[type=range]::-webkit-slider-runnable-track{border-radius:var(--radius-sm);background:var(--track,var(--control-edge));height:5px}input[type=range]::-moz-range-track{border-radius:var(--radius-sm);background:var(--track,var(--control-edge));height:5px}input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;border:3px solid var(--brand);width:19px;height:19px;box-shadow:0 2px 0 var(--brand-dark);cursor:grab;background:#fff;border-radius:50%;margin-top:-7px}input[type=range]::-moz-range-thumb{border:3px solid var(--brand);width:13px;height:13px;box-shadow:0 2px 0 var(--brand-dark);cursor:grab;background:#fff;border-radius:50%}input[type=range]:focus-visible::-webkit-slider-thumb{outline:3px solid var(--brand);outline-offset:3px}input[type=range]:focus-visible::-moz-range-thumb{outline:3px solid var(--brand);outline-offset:3px}.parameter-presets{grid-template-columns:repeat(auto-fit,minmax(58px,1fr));gap:10px 7px;margin-top:2px;display:grid}.parameter-presets.is-only{margin-top:5px}.parameter-presets:has(>button:nth-child(4)){grid-template-columns:repeat(4,minmax(0,1fr))}.parameter-presets:has(>button:nth-child(4))>button{grid-column:span 2}.parameter-presets:has(>button:nth-child(4))>button:nth-child(odd):last-child{grid-column:2/span 2}.seg{flex-wrap:wrap;gap:7px;margin-top:5px;display:flex}.seg button{min-width:40px}.parameter-presets button,.seg button{height:34px;font-size:var(--fs-xs);border-radius:var(--radius);border:1.5px solid var(--control-edge);box-shadow:0 2px 0 var(--control-edge);color:var(--muted);background:#fff;padding:0 8px;font-weight:700;position:relative}.parameter-presets button:after,.seg button:after,.reset-scene:after,.scene-bottomline button:after{content:"";position:absolute;inset:-5px -3.5px}.reset-scene,.scene-bottomline button{position:relative}.parameter-presets button:not(:disabled):hover,.seg button:not(:disabled):hover{background:var(--paper-dark)}.parameter-presets button[aria-pressed=true],.seg button[aria-pressed=true]{background:var(--tint);border-color:var(--brand);color:var(--brand);box-shadow:0 2px 0 var(--brand)}.parameter-presets button:not(:disabled):active,.seg button:not(:disabled):active{box-shadow:none;transform:translateY(2px)}:is(.parameter-presets button,.seg button,.reset-scene,.scene-bottomline button){transition:border-color .15s,box-shadow .15s,background-color .15s,color .15s}.reset-scene:active{background:var(--line);color:var(--ink);transform:translateY(1px)}.scene-bottomline button:active{background:#24315a;transform:translateY(1px)}.seg button:disabled{opacity:.45;box-shadow:none;cursor:not-allowed;background:#fff;transform:none}.reveal-stops{grid-template-columns:repeat(6,minmax(0,1fr));display:grid}.reveal-stops>button{grid-column:span 2}.reveal-stops>button:nth-child(3n+1):last-child{grid-column:3/span 2}.reveal-stops>button:nth-child(3n+1):nth-last-child(2){grid-column:2/span 2}.reveal-stops button{height:auto;min-height:34px;line-height:var(--lh-heading);padding:4px}.lab-observation{border:1.5px solid var(--line);border-radius:var(--radius);background:var(--paper);margin-top:auto;padding:15px}.lab-observation .article-kicker{color:var(--muted);font-size:var(--fs-2xs)}.lab-observation p{font-size:var(--fs-sm);line-height:var(--lh-body);text-wrap:pretty;margin:6px 0 0;font-weight:600}.lab-observation__texts{display:grid}.lab-observation__texts>p{grid-area:1/1}.lab-observation__texts>.is-spare{visibility:hidden}.control__value>*{grid-area:1/1}.control__value>.is-spare{visibility:hidden}[dir=rtl] .control__value{justify-items:start}:root:lang(he){--font:"Archivo", "Heebo", system-ui, sans-serif;--mono:"DM Mono", "Heebo", ui-monospace, Menlo, monospace;--track-caps:0em;--track-label:.02em;--track-title:-.01em;--track-heading:-.02em;--track-display:-.02em;--lh-body:1.8;--lh-prose:2}:lang(he) :is(.scene-topline,.featured-art__top){font-family:var(--font)}@media (width<=1050px){:root{--split-gap:36px}}@media (width<=767px){.topbar{--gutter:18px;padding:19px var(--gutter)}.site-footer{padding:0 18px}.site-tagline{display:none}.topbar nav{gap:13px}.topbar nav a>span[aria-hidden],.topbar .nav-long{display:none}.topbar .nav-short{display:inline}.topbar .lang-switch{margin-inline-start:-2px;padding-inline-start:11px}.scene-viewport{min-height:360px}.scene-viewport--tall{min-height:580px}.scene-topline,.scene-bottomline{inset-inline:16px}.scene-topline{flex-wrap:wrap;align-items:start;row-gap:4px;top:14px}.hud-panel{gap:20px;padding:20px}.control-row{row-gap:20px}.hud-panel h3{display:none}.lab-observation{padding:12px 15px}.seg[role=group]>button{flex:1 1 0;min-width:max-content}}@media (width<=359px){.topbar{--gutter:14px;gap:8px}.topbar nav{gap:9px}.topbar .lang-switch{margin-inline-start:-1px;padding-inline-start:8px}.wordmark{font-size:var(--fs-lg)}.wordmark svg{width:24px;height:24px;margin-inline-end:7px}}@media (prefers-reduced-motion:reduce){:root{scroll-behavior:auto}*{transition:none!important}}@media (forced-colors:active){:is(.home-article-card,.learn-card,.state-card,.guide-chart,.practice,.teacher-card,.teacher-step,.progress-totals li,.progress-misconceptions li,.category-nav a,.lesson-status,.teacher-flag){border-color:canvastext}:is(.article-button,.check-toggle,.parameter-presets button,.seg button,.reset-scene,.scene-bottomline button,.teacher-float){border-color:buttontext}:is(.home-article-card,.learn-card--link,.category-nav a,.article-button:not(:disabled,[aria-disabled=true]),.check-toggle,.parameter-presets button:not(:disabled),.seg button:not(:disabled)):hover{border-color:highlight}.learn-card--link:has(:is(h2,h3,h4) a:focus-visible),.home-article-card:focus-visible{outline-color:highlight}:is(.reading-aside>nav a,.lesson-steps a,.page-index li a,.teacher-toc__lesson)[aria-current]{border-inline-start-color:highlight}.article-button--primary{forced-color-adjust:none;color:buttonface;background:buttontext;border-color:buttontext}.article-button--primary:not(:disabled,[aria-disabled=true]):hover{color:highlighttext;filter:none;background:highlight;border-color:highlight}.article-button:is(:disabled,[aria-disabled=true]),.seg button:disabled{color:graytext;opacity:1;border-color:graytext}:is(.parameter-presets button,.seg button,.check-toggle)[aria-pressed=true]{forced-color-adjust:none;color:highlighttext;background:highlight;border-color:highlight}.check-toggle[aria-pressed=true] .check-toggle__box{background:highlighttext;border-color:highlighttext}.check-toggle[aria-pressed=true] .check-toggle__box:after{border-color:highlight}.lesson-status[data-state=done]{forced-color-adjust:none;color:highlighttext;background:highlight;border-color:highlight}.lesson-status[data-state=started]{border-color:highlight}}.article-shell{max-width:1320px;margin:auto;padding:0 44px}.article-breadcrumb{font-size:var(--fs-xs);color:var(--muted);margin-bottom:34px;font-weight:600}.article-breadcrumb ol{clip-path:inset(-20px -4px);flex-wrap:wrap;align-items:center;gap:10px 0;margin:0;padding:0;list-style:none;display:flex}.article-breadcrumb li{align-items:center;min-width:0;display:inline-flex}.article-breadcrumb li:not(:last-child){margin-inline-end:30px}.article-breadcrumb li+li{margin-inline-start:-30px}.article-breadcrumb li+li:before{content:"/" / "";text-align:center;inline-size:30px;color:var(--control-edge);flex:none}.article-breadcrumb a{color:var(--muted);align-items:center;min-height:44px;margin-block:-14px;display:inline-flex}.article-breadcrumb a:hover{color:var(--brand)}.article-breadcrumb [aria-current]{color:var(--ink);text-overflow:ellipsis;white-space:nowrap;max-width:32ch;overflow:hidden}.article-breadcrumb__back{display:none}@media (width<=767px){.article-breadcrumb--parent li:not(:nth-last-child(2)){display:none}.article-breadcrumb--parent li{margin:0}.article-breadcrumb--parent li:before{content:none}.article-breadcrumb--parent .article-breadcrumb__back{margin-inline-end:6px;display:inline}}.article-hero{padding:32px 0 40px}.article-hero__grid{grid-template-columns:var(--split);align-items:start;gap:var(--split-gap);display:grid}.article-kicker{color:var(--brand);font-size:var(--fs-2xs);letter-spacing:var(--track-caps);text-transform:uppercase;font-weight:800;line-height:var(--lh-ui);margin:0 0 14px}:lang(he) :is(.article-kicker,.featured-prompt .article-kicker,.scene-notes>.article-kicker,.lab-controls-heading .article-kicker,.lab-observation .article-kicker,.scene-chart__kicker){font-size:var(--fs-xs)}.article-hero h1{font-size:var(--fs-display);line-height:var(--lh-display);letter-spacing:var(--track-display);text-wrap:balance;max-width:660px;margin:0;font-weight:800}.title-stop{color:var(--brand)}.article-intro{max-width:405px}.article-intro>p{font-size:var(--fs-lg);line-height:var(--lh-body);color:var(--muted);margin:0 0 24px}.article-format{font-size:var(--fs-2xs);color:var(--muted);white-space:nowrap;margin-inline-start:16px;font-weight:600}.article-intro>.article-format{white-space:normal;margin:0;display:block}.article-button{height:34px;font-size:var(--fs-xs);color:var(--ink);border:1.5px solid var(--control-edge);border-radius:var(--radius);box-shadow:0 2px 0 var(--control-edge);cursor:pointer;background:#fff;justify-content:center;align-items:center;gap:8px;padding:0 14px;font-weight:700;transition:border-color .15s,box-shadow .15s,background-color .15s,filter .15s;display:inline-flex;position:relative}.article-button:before{content:"";position:absolute;inset:-6px 0}.article-button:hover{text-decoration:none}.article-button:not(:disabled,[aria-disabled=true]):hover{border-color:var(--brand);box-shadow:0 2px 0 var(--brand)}.article-button--primary{color:#fff;background:var(--brand);border-color:var(--brand-dark);box-shadow:0 2px 0 var(--brand-dark)}.article-button--primary:not(:disabled,[aria-disabled=true]):hover{border-color:var(--brand-dark);box-shadow:0 2px 0 var(--brand-dark);filter:brightness(1.12)}.article-button--danger{color:var(--danger);border-color:var(--danger);box-shadow:0 2px 0 var(--danger)}.article-button--danger:not(:disabled,[aria-disabled=true]):hover{border-color:var(--danger);box-shadow:0 2px 0 var(--danger);background:var(--danger-tint)}.article-button:not(:disabled,[aria-disabled=true]):active{box-shadow:none;transform:translateY(2px)}.article-button:is(:disabled,[aria-disabled=true]){opacity:.5;cursor:not-allowed;filter:none;box-shadow:none;transform:none}.article-button--small{gap:10px;height:30px;padding:0 11px}.article-button--small:before{inset:-7px 0}.article-jumps{border-top:1.5px solid var(--line);border-bottom:1.5px solid var(--line);flex-wrap:wrap;gap:36px;padding:18px 0;display:flex}.article-jumps a{color:var(--ink);font-size:var(--fs-xs);margin:-10px 0;padding:10px 0;font-weight:700;display:inline-block}.article-jumps a span{color:var(--brand);font-family:var(--mono);font-weight:400;font-size:var(--fs-xs);margin-inline-end:8px}.lab-section{padding-top:44px}.section-heading{grid-template-columns:var(--split);align-items:start;column-gap:var(--split-gap);margin-bottom:23px;display:grid}.section-heading .article-kicker{margin-bottom:10px}.section-heading h2{font-size:var(--fs-section);line-height:var(--lh-heading);letter-spacing:var(--track-heading);margin:0;font-weight:800}.section-heading>p{max-width:405px;font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--muted);grid-column:2;margin:0 0 2px}.article-lab{border:1.5px solid var(--line-strong);border-radius:var(--radius-lg);min-height:540px;box-shadow:0 4px 0 var(--line);background:#fff;overflow:hidden}.article-lab astro-island{display:block}.scene-workspace{grid-template-columns:minmax(0,1fr) 312px;min-height:540px;display:grid}.scene-workspace--charts{grid-template-columns:272px minmax(0,1fr) 312px;grid-template-areas:"charts view controls"}.scene-workspace--charts>.scene-viewport{grid-area:view}.scene-workspace--charts>.scene-charts{border-inline-end:1.5px solid var(--line);grid-area:charts}.scene-workspace--charts>:is(.hud-panel,.lab-loading__status){grid-area:controls}.scene-workspace--notes:not(.scene-workspace--charts){grid-template-areas:"view controls""notes controls"}.scene-workspace--notes:not(.scene-workspace--charts)>.scene-viewport{grid-area:view}.scene-workspace--notes:not(.scene-workspace--charts)>.scene-notes{grid-area:notes}.scene-workspace--notes:not(.scene-workspace--charts)>:is(.hud-panel,.lab-loading__status){grid-area:controls}.scene-charts>.scene-notes{border-top:1.5px solid var(--line);margin-top:auto;padding:16px 0 0}.lab-loading{min-height:var(--lab-height,540px)}.lab-loading__status{flex-direction:column;justify-content:center;padding:23px;display:flex}.lab-loading__status p{font-size:var(--fs-sm);line-height:var(--lh-body);margin:10px 0 0}.lab-caption{font-size:var(--fs-xs);line-height:var(--lh-body);color:var(--muted);justify-content:space-between;gap:16px;margin:16px 0 0;display:flex}@media (width>=768px){.lab-caption:has(>:nth-child(2)){grid-template-columns:var(--split);column-gap:var(--split-gap);display:grid}.lab-caption>span:last-child:not(:only-child){max-width:72ch}}.lab-caption>span:first-child>span{color:var(--brand);font-size:var(--fs-md);line-height:var(--lh-display);margin-inline-end:5px}.exhibit-section .article-lab{min-height:0}.exhibit__closed{aspect-ratio:var(--poster-ratio,918 / 540);background:var(--studio);min-height:300px;position:relative;overflow:hidden}.exhibit__closed--tall{aspect-ratio:auto;height:min(620px,80vh)}.exhibit__closed--tall:before{content:"";background:var(--poster-src,none) center / cover;filter:blur(28px)brightness(.85);position:absolute;inset:-40px}.exhibit__closed--tall .scene-poster{object-fit:contain}.exhibit__actions{z-index:1;inset-inline:0;background:linear-gradient(#0b0f1a00,#0b0f1adb);flex-wrap:wrap;align-items:center;gap:12px 18px;padding:40px 20px 18px;display:flex;position:absolute;bottom:0}.exhibit__note{max-width:46ch;font-size:var(--fs-xs);line-height:var(--lh-ui);color:#e6ecf7;margin:0}.lab-caption .exhibit__credit a{color:inherit}@media (width<=767px){.exhibit__closed{aspect-ratio:auto;height:auto;min-height:0}.exhibit__closed:before{content:none}.exhibit__closed .scene-poster{height:auto;display:block;position:static}.exhibit__actions{background:var(--studio);padding:14px 16px 16px;position:static}}.compare-section{padding:78px 0 0}.state-cards{grid-template-columns:repeat(3,minmax(0,1fr));gap:18px;display:grid}.state-card{border:1.5px solid var(--line-strong);border-radius:var(--radius-lg);box-shadow:0 2px 0 var(--line-strong);background:#fff;align-content:start;padding:23px}.state-card__top{justify-content:space-between;align-items:center;display:flex}.state-card__top .article-kicker{color:var(--muted);margin:0}.state-number{font-family:var(--mono);color:var(--muted);font-size:var(--fs-xs)}.particle-diagram{width:190px;max-width:100%;height:135px;fill:var(--brand);margin:23px auto 22px;display:block}@media (width>=768px){.state-card:has(>.particle-diagram){grid-template-columns:minmax(0,1fr) 84px;align-content:start;column-gap:16px;display:grid}.state-card:has(>.particle-diagram)>:not(.particle-diagram,h3){grid-column:1/-1}.state-card:has(>.particle-diagram)>.state-card__top{margin-bottom:14px}.state-card:has(>.particle-diagram)>h3{grid-area:2/1;align-self:center;margin:0}.state-card>.particle-diagram{grid-area:2/2;align-self:center;width:84px;height:60px;margin:0}.state-card:has(>.particle-diagram)>h3+p{margin-top:14px}}.guide-still{border-radius:var(--radius);background:#141a24;width:100%;min-width:0;max-width:100%;height:auto;margin:18px 0 20px;display:block}.particle-diagram path{fill:none;stroke:var(--line);stroke-width:1.5px;vector-effect:non-scaling-stroke}.particle-diagram .diagram-bond{stroke:var(--line-strong);stroke-dasharray:2 3}.particle-diagram .diagram-trail{stroke:var(--brand);stroke-linecap:round}.particle-diagram .diagram-mark{stroke:#fff;stroke-width:4.5px;stroke-linecap:round;vector-effect:none}.state-card h3{font-size:var(--fs-2xl);letter-spacing:var(--track-heading);line-height:var(--lh-heading);margin:0 0 13px;font-weight:800}.state-card>p{color:var(--muted);font-size:var(--fs-sm);line-height:var(--lh-body);min-height:94px;margin:0 0 20px}.state-card dl{border-top:1.5px solid var(--line);margin:0;padding-top:12px}.state-card dl div{font-size:var(--fs-xs);line-height:var(--lh-ui);grid-template-columns:73px 1fr;gap:8px;padding:7px 0;display:grid}.state-card dt{color:var(--muted)}.state-card dd{text-align:end;margin:0;font-weight:600}.state-card dd.state-figure{font-variant-numeric:tabular-nums;white-space:nowrap}.guide-chart{border:1.5px solid var(--line-strong);border-radius:var(--radius-lg);box-shadow:0 2px 0 var(--line-strong);background:#fff;grid-template-columns:minmax(0,1.5fr) minmax(0,1fr);align-items:center;gap:36px;margin-top:18px;padding:23px;display:grid}.guide-chart svg{width:100%;height:auto;font-family:var(--mono);display:block}.guide-chart .article-kicker{color:var(--muted);margin:0 0 12px}.guide-chart h3{font-size:var(--fs-2xl);letter-spacing:var(--track-heading);line-height:var(--lh-heading);margin:0 0 13px;font-weight:800}.guide-chart p{color:var(--muted);font-size:var(--fs-sm);line-height:var(--lh-body);margin:0}.matter-takeaway{grid-template-columns:var(--split);align-items:start;gap:12px var(--split-gap);border-bottom:1.5px solid var(--line);border-top:1.5px solid var(--line);grid-template-rows:auto 1fr;margin-top:24px;padding:25px 0;display:grid}.matter-takeaway .article-kicker{grid-area:1/1;margin:0}.matter-takeaway p{font-size:var(--fs-md);line-height:var(--lh-body);color:var(--muted);grid-area:1/2/3/3;margin:0}.matter-takeaway .molecule-formula{white-space:normal;text-wrap:balance;overflow-wrap:anywhere;grid-area:2/1;justify-self:start;min-width:0;max-width:100%}.matter-takeaway strong{color:var(--ink);font-weight:700}.molecule-formula{font-size:var(--fs-2xl);color:var(--brand);text-align:start;letter-spacing:var(--track-figure);white-space:nowrap;font-weight:700}.molecule-formula span{font-size:var(--fs-xl);color:var(--muted);margin:0 8px;font-weight:400}.reading-layout{grid-template-columns:280px minmax(0,1fr);gap:110px;padding:80px 0;display:grid}.reading-aside{align-self:start;position:sticky;top:30px}.reading-aside h2{font-size:var(--fs-2xl);letter-spacing:var(--track-heading);font-weight:800;line-height:var(--lh-heading);margin:0 0 26px}.reading-aside>nav{border-top:1.5px solid var(--line);display:grid}.reading-aside>nav a{border-bottom:1.5px solid var(--line);font-size:var(--fs-sm);line-height:var(--lh-ui);color:var(--muted);justify-content:space-between;gap:12px;padding:14px 0;display:flex}.reading-aside>nav a:hover{color:var(--brand)}:is(.reading-aside>nav a,.lesson-steps a,.page-index li a,.teacher-toc__lesson){border-inline-start:3px solid #0000;padding-inline-start:12px}:is(.reading-aside>nav a,.lesson-steps a,.page-index li a,.teacher-toc__lesson)[aria-current]{color:var(--ink);border-inline-start-color:var(--brand);text-decoration:none}@media (prefers-reduced-motion:no-preference){:is(.reading-aside>nav a,.lesson-steps a,.page-index li a,.teacher-toc__lesson){transition:color .15s,border-color .15s}}.page-index{border-top:1.5px solid var(--line);border-bottom:1.5px solid var(--line);display:none}.page-index>summary{min-height:44px;font-size:var(--fs-xs);color:var(--ink);cursor:pointer;align-items:center;gap:10px;padding:6px 0;font-weight:700;list-style:none;display:flex}.page-index>summary::-webkit-details-marker{display:none}.page-index>summary:after{content:"";border:solid var(--brand);border-width:0 2px 2px 0;flex:none;width:7px;height:7px;margin-inline-start:auto;transform:translateY(-2px)rotate(45deg)}.page-index[open]>summary:after{transform:translateY(2px)rotate(-135deg)}.page-index__count{font-family:var(--mono);font-weight:400;font-size:var(--fs-xs);color:var(--brand)}.page-index__current{text-overflow:ellipsis;white-space:nowrap;min-width:0;color:var(--muted);font-weight:600;overflow:hidden}.page-index ol{counter-reset:index;margin:0;padding:0 0 8px;list-style:none}.page-index li{counter-increment:index}.page-index li a{border-top:1px solid var(--line);min-height:44px;font-size:var(--fs-sm);line-height:var(--lh-ui);color:var(--ink);align-items:baseline;gap:10px;padding:12px 0;display:flex}.page-index li a:before{content:counter(index, decimal-leading-zero);font-family:var(--mono);font-size:var(--fs-xs);color:var(--brand);flex:none}:is(.back-to-scene a,.back-to-lab){min-height:44px;font-size:var(--fs-sm);font-weight:600;line-height:var(--lh-ui);color:var(--brand);align-items:center;gap:6px;display:inline-flex}.back-to-lab{margin-top:14px}.prose{max-width:650px;font-size:var(--fs-md);line-height:var(--lh-prose);color:var(--muted)}.prose h2{color:var(--ink);font-size:var(--fs-2xl);line-height:var(--lh-heading);letter-spacing:var(--track-title);margin:1.7em 0 .7em;scroll-margin-top:30px;font-weight:800}.prose h2:first-child{margin-top:0}.prose p{text-wrap:pretty;margin:0 0 1.1em}.prose strong{color:var(--ink);font-weight:700}.prose blockquote{border-inline-start:3px solid var(--brand);font-size:var(--fs-md);background:#fff;margin:28px 0;padding:14px 20px}.prose blockquote strong{color:var(--ink)}.prose blockquote p{margin:0}.prose blockquote .back-to-scene{margin:4px 0 -10px}.prose footer{border-top:1.5px solid var(--line);font-size:var(--fs-sm);color:var(--muted);margin-top:56px;padding-top:20px}.prose footer ul{padding-inline-start:18px}.prose table{border-collapse:collapse;width:max-content;max-width:100%;font-size:var(--fs-sm);line-height:var(--lh-ui);margin:0 0 1.4em;display:block;overflow-x:auto}.prose th,.prose td{text-align:start;vertical-align:top;border-bottom:1.5px solid var(--line);padding:8px 14px}.prose th{color:var(--ink);border-bottom-color:var(--line-strong);font-weight:700}.prose th:first-child,.prose td:first-child{padding-inline-start:0}.article-footer{border-top:1.5px solid var(--line);grid-template-columns:var(--split);column-gap:var(--split-gap);align-items:start;padding:26px 0 40px;display:grid}.article-footer>.wordmark{justify-self:start}.article-footer__end{justify-content:space-between;align-items:start;gap:24px;display:flex}.article-footer p,.article-footer__top{color:var(--muted);font-size:var(--fs-xs);line-height:var(--lh-body);margin:0}.article-footer p{text-wrap:pretty}.article-footer__top{white-space:nowrap;flex:none;align-items:baseline;gap:8px;display:inline-flex;position:relative}.article-footer__top:after{content:"";inset-inline:-4px;position:absolute;top:calc(50% - 22px);bottom:calc(50% - 22px)}.licence{white-space:nowrap;unicode-bidi:isolate}.licence-end{white-space:nowrap}@media (width>=1500px){.article-hero{padding-top:40px;padding-bottom:50px}}@media (width<=1050px){.article-shell{padding:0 28px}.topbar{--gutter:28px;padding:22px var(--gutter)}.site-footer{padding:0 28px}.article-intro>p{font-size:var(--fs-md)}.article-format{display:none}.scene-workspace{grid-template-columns:minmax(0,1fr) 280px}.scene-workspace--charts{grid-template-columns:minmax(0,1fr) 280px;grid-template-areas:"view controls""charts controls"}.scene-workspace--charts>.scene-charts{border-inline-end:0;border-top:1.5px solid var(--line);grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:20px 26px;display:grid}.scene-workspace--charts .scene-chart+.scene-chart{border-top:0;padding-top:0}.scene-charts>.scene-notes{border-top:0;border-bottom:1.5px solid var(--line);order:-1;grid-column:1/-1;margin:0;padding:0 0 16px}.hud-panel,.state-card{padding:20px}.state-card>p{min-height:120px}.state-card dl div{grid-template-columns:1fr;gap:4px}.state-card dd{text-align:start}.reading-layout{grid-template-columns:230px minmax(0,1fr);gap:54px}}@media (width<=767px){.guide-chart{grid-template-columns:1fr;gap:18px}.prose th,.prose td{padding-inline:10px}.prose th:first-child,.prose td:first-child{padding-inline-start:0}.article-shell{padding:0 18px}.topbar{--gutter:18px;padding:19px var(--gutter)}.site-footer{padding:0 18px}.article-hero{padding:25px 0 30px}.article-breadcrumb{margin-bottom:28px}.article-hero__grid{grid-template-columns:1fr;gap:22px}.article-hero h1{font-size:var(--fs-display-phone);hyphens:auto;overflow-wrap:break-word;max-width:480px}.article-intro{max-width:490px}.article-intro>p{margin-bottom:20px}.article-format{display:inline}.article-jumps{gap:18px;padding:16px 0}.article-jumps a span{display:none}:is(.home-principles,.progress-jumps){text-wrap:balance;font-size:var(--fs-xs);line-height:var(--lh-ui);padding:10px 0;display:block}:is(.home-principles,.progress-jumps) a{margin:-4px 0;vertical-align:top;margin-inline-end:15px;padding:10px 0}:is(.home-principles,.progress-jumps) a:last-child{margin-inline-end:0}.lab-section{padding-top:32px}.section-heading{margin-bottom:20px;display:block}.section-heading>p{max-width:none;margin-top:12px}.article-lab{min-height:0}.scene-workspace{grid-template-columns:1fr}.scene-workspace--charts{grid-template-columns:1fr;grid-template-areas:"view""charts""controls"}.scene-workspace--charts>.scene-charts{border-bottom:1.5px solid var(--line);flex-direction:column;gap:16px;display:flex}.scene-workspace--charts .scene-chart+.scene-chart{border-top:1.5px solid var(--line);padding-top:16px}.scene-workspace--notes:not(.scene-workspace--charts){grid-template-areas:"view""notes""controls"}.scene-workspace--notes:not(.scene-workspace--charts)>.scene-notes{border-bottom:1.5px solid var(--line)}.lab-loading{min-height:0}.lab-caption{gap:3px;display:grid}.compare-section{padding-top:48px}.state-cards{grid-template-columns:1fr;gap:16px}.state-card{grid-template-columns:minmax(0,1fr) 84px;column-gap:16px;padding:22px;display:grid}.state-card__top{grid-column:1/-1;margin-bottom:18px}.particle-diagram{grid-area:2/2;align-self:center;width:84px;height:60px;margin:0}.guide-still{grid-area:2/1/auto/-1;width:100%;min-width:0;max-width:100%;margin:0 0 18px}.state-card:has(.guide-still) h3{grid-area:3/1/auto/-1}.state-card:has(.guide-still)>p{grid-area:4/1/auto/-1}.state-card h3{grid-area:2/1;align-self:center;margin:0}.state-card:not(:has(>.particle-diagram)) h3{grid-column:1/-1}.state-card>p{grid-area:3/1/auto/-1;min-height:0;margin:14px 0 20px}.state-card dl{grid-column:1/-1}.state-card dl div{font-size:var(--fs-sm);line-height:var(--lh-body);grid-template-columns:75px minmax(0,1fr)}.state-card dd{text-align:end;overflow-wrap:anywhere}.state-card dd.state-figure{white-space:normal}.matter-takeaway{grid-template-rows:none;grid-template-columns:1fr;gap:13px;padding:23px 0}.matter-takeaway :is(.article-kicker,p,.molecule-formula){grid-area:auto}.molecule-formula{text-align:start}.matter-takeaway .molecule-formula{min-width:0}.reading-layout{padding:48px 0;display:block}.reading-aside{margin-bottom:32px;position:static}.reading-aside h2 br,.reading-aside>nav{display:none}.page-index{display:block}.prose h2{font-size:var(--fs-xl)}.article-footer{grid-template-columns:minmax(0,1fr) auto;gap:18px}.article-footer__end{display:contents}.article-footer p{order:3;grid-column:1/-1}}@media (width<=380px){.article-format{display:none}}@media (width<=399px){:is(.home-principles,.progress-jumps) a{margin-inline-end:5px}:is(.home-principles,.progress-jumps) a:last-child{margin-inline-end:0}}.lesson-status{font-size:var(--fs-2xs);font-weight:700;line-height:var(--lh-display);border:1px solid var(--control-edge);border-radius:var(--radius-sm);color:var(--muted);white-space:nowrap;background:#fff;padding:4px 7px;display:inline-block}.lesson-status[data-state=started]{color:var(--brand-dark);border-color:var(--brand)}.lesson-status[data-state=done]{color:#fff;background:var(--brand);border-color:var(--brand-dark)}.lesson-status[data-state=done]:before{content:"✓ "}.lesson-status[hidden]{display:none}.check-toggle{color:var(--ink);cursor:pointer;gap:10px;font-family:inherit}.check-toggle[hidden]{display:none}.check-toggle__box{border:1.5px solid var(--control-edge);border-radius:var(--radius-sm);background:#fff;flex:none;width:16px;height:16px;position:relative}.check-toggle[aria-pressed=true]{background:var(--tint);border-color:var(--brand);color:var(--brand);box-shadow:0 2px 0 var(--brand)}.check-toggle[aria-pressed=true] .check-toggle__box{background:var(--brand);border-color:var(--brand)}.check-toggle[aria-pressed=true] .check-toggle__box:after{content:"";border:2px solid #fff;border-width:0 2px 2px 0;width:4px;height:9px;position:absolute;top:0;left:4px;transform:rotate(45deg)}.hero-actions{flex-wrap:wrap;align-items:center;gap:10px;display:flex}@media (width<=767px){.article-hero__lead{display:contents}.article-hero__grid>.article-intro{order:1}.article-hero__grid .hero-after{order:2;margin-top:0}}.read-toggle{width:fit-content}.hero-actions:has(.read-toggle:not([hidden])) .article-format{display:none}.read-hint{text-wrap:balance;font-size:var(--fs-xs);line-height:var(--lh-ui);color:var(--muted);margin-top:8px;display:block}.read-hint[hidden]{display:none}.article-learn{padding:8px 0 56px}.article-learn__list{border-top:1.5px solid var(--line);margin:0;padding:0;list-style:none}.article-learn__list li{grid-template-columns:minmax(0, 1fr) var(--row-meta) 32px;border-bottom:1.5px solid var(--line);align-items:baseline;column-gap:0;padding:16px 0;display:grid;position:relative}.article-learn__title{flex-wrap:wrap;grid-area:1/1;align-items:center;gap:6px 12px;padding-inline-end:24px;display:flex}.article-learn__list a{font-size:var(--fs-lg);letter-spacing:var(--track-title);color:var(--ink);font-weight:800}.article-learn__where{text-align:end;font-size:var(--fs-sm);line-height:var(--lh-ui);color:var(--muted);grid-area:1/2}.article-learn__go{font-size:var(--fs-lg);color:var(--brand);grid-area:1/3;justify-self:end}@media (width<=767px){.article-learn__list li{grid-template-columns:minmax(0,1fr) auto;gap:4px 14px}.article-learn__title{padding:0}.article-learn__where{text-align:start;grid-area:2/1}.article-learn__go{grid-column:2}}.article-learn__list a:after{content:"";position:absolute;inset:0}.article-learn__list a:focus-visible{outline:none}.article-learn__list li:has(a:focus-visible){outline:3px solid var(--brand);outline-offset:2px}.article-learn__list li:hover a{color:var(--brand);text-decoration:none}.lesson-facts{flex-wrap:wrap;align-items:baseline;gap:8px 24px;margin-top:24px;display:flex}.lesson-facts__meta{font-size:var(--fs-sm);color:var(--muted);margin:0;font-weight:600}.lesson-articles{font-size:var(--fs-sm);flex-wrap:wrap;gap:8px 16px;margin:0;padding:0;font-weight:600;list-style:none;display:flex}.lesson-articles a{margin:-10px 0;padding:10px 0;display:inline-block}.not-found{padding-bottom:56px}.not-found .article-hero{padding-bottom:32px}.not-found__find{border-top:1.5px solid var(--line);text-align:center;padding:28px 0 0}.not-found__find .home-search{justify-content:center;max-width:480px;margin-inline:auto}.not-found__find .home-search input{flex:auto}.not-found__noscript{font-size:var(--fs-sm);color:var(--muted);margin:0 0 14px}.not-found :is(.not-found__find,.not-found__start)>.article-kicker{margin-bottom:10px}.not-found :is(.not-found__find,.not-found__start) h2{font-size:var(--fs-section);letter-spacing:var(--track-heading);font-weight:800;line-height:var(--lh-heading);margin:0 0 18px}.not-found__search{margin-bottom:20px}.not-found__search .article-button{height:44px}.not-found__start{border-top:1.5px solid var(--line);margin-top:36px;padding-top:28px}.not-found__cards{grid-template-columns:repeat(auto-fill,minmax(min(100%,300px),1fr));gap:20px;display:grid}.not-found__cards>.home-article-card{padding-bottom:calc(22px - (var(--lh-body) - 1) * var(--fs-sm) / 2)}.not-found__cards>*{grid-row:span 2;grid-template-rows:subgrid;grid-template-columns:minmax(0,1fr) auto;gap:0 12px;min-width:0;display:grid}@media (width<=767px){.home-search.not-found__search{flex-wrap:nowrap;gap:8px}.home-search.not-found__search input{flex:auto}.home-search.not-found__search .article-button{flex:none}}