:root{color-scheme:light;--ink:#202122;--ink-soft:#3a3d40;--muted:#54595d;--paper:#fbfaf6;--surface:#fff;--surface-muted:#f1f2f3;--line:#a2a9b1;--line-light:#c8ccd1;--link:#0645ad;--link-hover:#0b0080;--accent:#2f4f4f;--accent-pale:#edf2f1;--warning:#7b342c;--focus:#0b57d0;--site-max:90rem;--measure:46rem;--left-rail:13rem;--right-rail:15rem;--grid-gap:2rem;font-synthesis:none}*,:before,:after{box-sizing:border-box}html{color:var(--ink);background:var(--paper);scroll-behavior:smooth;text-rendering:optimizelegibility;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica,Arial,sans-serif;font-size:100%;line-height:1.62}body{min-width:20rem;margin:0}a{color:var(--link);text-underline-offset:.16em;text-decoration-thickness:.0625em}a:visited{color:var(--link-hover)}a:hover{color:var(--link-hover);text-decoration-thickness:.125em}a:focus-visible,summary:focus-visible,button:focus-visible,input:focus-visible,.table-wrap:focus-visible,[tabindex="-1"]:focus-visible{outline:3px solid var(--focus);outline-offset:3px;border-radius:.0625rem}::selection{color:#fff;background:#315d83}h1,h2,h3,h4{color:var(--ink);font-family:Georgia,Times New Roman,Times,serif;font-weight:500}p,ul,ol,blockquote,figure,table{margin-block:0 1rem}img,svg{max-width:100%;height:auto}button,input{font:inherit}.skip-link{z-index:100;color:#fff;background:var(--ink);padding:.55rem .8rem;position:fixed;top:.75rem;left:.75rem;transform:translateY(-200%)}.skip-link:focus{color:#fff;transform:translateY(0)}.site-header{border-top:4px solid var(--accent);border-bottom:1px solid var(--line);background:var(--surface)}.header-inner{width:min(calc(100% - 2rem), var(--site-max));justify-content:space-between;align-items:center;gap:1.5rem;min-height:5.25rem;margin-inline:auto;display:flex}.brand{min-width:max-content;color:var(--ink);align-items:center;gap:.7rem;text-decoration:none;display:inline-flex}.brand:visited{color:var(--ink)}.brand img{width:2.625rem;height:2.625rem;display:block}.brand-copy{line-height:1.12;display:grid}.brand-copy strong{letter-spacing:-.01em;font-family:Georgia,Times New Roman,Times,serif;font-size:1.22rem;font-weight:600}.brand-copy small{color:var(--muted);letter-spacing:.015em;margin-top:.24rem;font-size:.72rem}.site-menu{display:none}.desktop-menu,.site-menu-panel{flex-direction:column;align-items:flex-end;gap:.55rem;display:flex}.primary-nav,.resource-nav{flex-wrap:wrap;justify-content:flex-end;align-items:center;display:flex}.primary-nav{gap:.2rem 1.1rem}.resource-nav{gap:.2rem .8rem;font-size:.78rem}.resource-nav>span{color:var(--muted);letter-spacing:.04em;text-transform:uppercase;font-weight:700}.primary-nav a,.resource-nav a{color:var(--ink-soft);border-bottom:2px solid #0000;line-height:1.75;text-decoration:none}.primary-nav a{font-size:.9rem}.primary-nav a:hover,.resource-nav a:hover,.primary-nav a[aria-current=page],.resource-nav a[aria-current=page]{border-bottom-color:var(--accent);color:var(--ink)}.primary-nav a[aria-current=page],.resource-nav a[aria-current=page]{font-weight:700}.page-shell{width:min(calc(100% - 2rem), var(--site-max));margin-inline:auto;padding-block:.65rem 4.5rem}.breadcrumbs{border-bottom:1px solid var(--line-light)}.breadcrumbs ol{color:var(--muted);flex-wrap:wrap;gap:.25rem;margin:0;padding:.35rem 0 .45rem;font-size:.78rem;list-style:none;display:flex}.breadcrumbs li:not(:last-child):after{color:var(--line);content:">";margin-inline:.25rem}.breadcrumbs a{color:var(--muted)}.article-header{max-width:var(--measure);margin:2.2rem 0 1.4rem calc(var(--left-rail) + var(--grid-gap))}.article h1{letter-spacing:-.025em;text-wrap:balance;max-width:18ch;margin:0;font-size:clamp(2.2rem,5vw,3.35rem);line-height:1.04}.article-deck{max-width:66ch;color:var(--muted);margin:.85rem 0 0;font-family:Georgia,Times New Roman,Times,serif;font-size:1.05rem;line-height:1.48}.reference-grid{grid-template-columns:minmax(10rem, var(--left-rail)) minmax(0, var(--measure)) minmax(12rem, var(--right-rail));gap:var(--grid-gap);align-items:start;display:grid}.contents-rail{scrollbar-gutter:stable;grid-column:1;align-self:start;max-height:calc(100vh - 2rem);position:sticky;top:1rem;overflow-y:auto}.article-body{grid-column:2;min-width:0}.facts-rail{grid-column:3;min-width:0}.article>:not(.article-header,.reference-grid){max-width:var(--measure);margin-left:calc(var(--left-rail) + var(--grid-gap))}.article-meta{color:var(--muted);flex-wrap:wrap;gap:.2rem 1.1rem;margin:0 0 1.35rem;font-size:.78rem;line-height:1.4;display:flex}.article-meta a{color:inherit}.article-introduction{border-bottom:1px solid var(--line-light);padding-bottom:.45rem}.article-body>p,.article-body li,.article-body td,.article-body th,.article-body dd,.article>p,.article>li{max-width:72ch}.lede,.article-introduction .lede{color:var(--ink-soft);font-family:Georgia,Times New Roman,Times,serif;font-size:1.18rem;line-height:1.55}.content-section{margin-block:2.25rem}.content-section>h2,.article-body>h2,.blog-article>h2,.quiz-block>h2,.further-watching>h2,.revision-history>h2{border-bottom:1px solid var(--line);margin:0 0 .85rem;padding-bottom:.25rem;font-size:1.65rem;line-height:1.24}.content-section>h3,.article-body>h3,.blog-article>h3,.faq-category>h3,.revision-history h3{margin:1.65rem 0 .55rem;font-size:1.23rem;line-height:1.3}.section-heading,.article-body h2,.article-body h3,.blog-article h2,.blog-article h3,.quiz-block,.faq-category,.editorial-figure,.source-list>li{scroll-margin-top:1rem}.section-heading{justify-content:space-between;align-items:baseline;gap:1rem;display:flex}.heading-anchor{color:var(--muted);opacity:0;padding-inline:.25rem;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;font-size:.8em;font-weight:400;text-decoration:none}.section-heading:hover .heading-anchor,.heading-anchor:focus-visible{opacity:1}.eyebrow,.card-eyebrow,.figure-label{color:var(--warning);letter-spacing:.075em;text-transform:uppercase;margin:0 0 .2rem;font-size:.72rem;font-weight:750}.definition-box{border:1px solid var(--line);border-left:4px solid var(--accent);background:var(--accent-pale);margin:1.65rem 0 2.2rem;padding:1rem 1.1rem}.definition-box h2{border:0;margin:0 0 .35rem;font-size:1.22rem}.definition-box p:last-child,.section-note:last-child,blockquote p:last-child,.info-card p:last-child,.quick-facts dd,.further-watching p:last-child{margin-bottom:0}.section-note{border-left:3px solid var(--line);color:var(--ink-soft);background:var(--surface-muted);padding:.72rem .9rem;font-size:.93rem}.article-list{padding-left:1.35rem}.article-list li{margin-bottom:.48rem;padding-left:.15rem}blockquote{border-left:4px solid var(--line);color:var(--ink-soft);margin:1.35rem 0;padding:.35rem 0 .35rem 1rem;font-family:Georgia,Times New Roman,Times,serif;font-size:1.04rem}blockquote footer{color:var(--muted);flex-wrap:wrap;gap:.2rem .55rem;margin-top:.6rem;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;font-size:.8rem;display:flex}blockquote footer span:not(:last-child):after,blockquote footer cite:not(:last-child):after{content:","}.citation-links{margin-left:.15em;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;font-size:.7em;font-style:normal;font-weight:600;line-height:0}.citation-links a{white-space:nowrap;text-decoration:none}.section-sources{color:var(--muted);gap:.35rem;margin-top:1.2rem;font-size:.78rem;display:flex}.section-sources>span:first-child{font-weight:700}.quick-facts{position:sticky;top:1rem}.rail-heading{border-bottom:1px solid var(--line);color:var(--ink);letter-spacing:.06em;text-transform:uppercase;margin:0 0 .45rem;padding-bottom:.35rem;font-size:.76rem;font-weight:750}.table-of-contents ol{margin:0;padding:0;font-size:.78rem;line-height:1.38;list-style:none}.table-of-contents li{border-left:2px solid var(--line-light);margin:0}.table-of-contents li.nested{padding-left:.65rem}.table-of-contents a{color:var(--muted);padding:.24rem 0 .24rem .7rem;text-decoration:none;display:block}.table-of-contents a:hover,.table-of-contents a:focus-visible{border-left-color:var(--accent);color:var(--link);text-decoration:underline}.quick-facts{border:1px solid var(--line);background:var(--surface);font-size:.8rem;line-height:1.42}.quick-facts h2{color:#fff;background:var(--accent);letter-spacing:.025em;margin:0;padding:.6rem .7rem;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;font-size:.82rem;font-weight:750}.quick-facts dl{margin:0}.quick-facts dl>div{border-bottom:1px solid var(--line-light);padding:.55rem .7rem}.quick-facts dl>div:last-child{border-bottom:0}.quick-facts dt{color:var(--muted);letter-spacing:.045em;text-transform:uppercase;font-size:.69rem;font-weight:750}.quick-facts dd{margin:.12rem 0 0}.quick-facts small{color:var(--muted);margin-top:.18rem;line-height:1.35;display:block}.table-wrap{border:1px solid var(--line);background:var(--surface);scrollbar-width:thin;max-width:100%;margin:1.25rem 0;overflow-x:auto}.table-description{border-bottom:1px solid var(--line);color:var(--muted);background:var(--surface-muted);margin:0;padding:.55rem .75rem;font-size:.8rem}table{border-collapse:collapse;width:100%;min-width:38rem;margin:0;font-size:.9rem;line-height:1.45}caption{border-bottom:1px solid var(--line);text-align:left;padding:.62rem .75rem;font-weight:700}th,td{border-right:1px solid var(--line-light);border-bottom:1px solid var(--line-light);vertical-align:top;text-align:left;padding:.62rem .7rem}tr>:last-child{border-right:0}tbody tr:last-child>*{border-bottom:0}thead th{color:var(--ink);background:#eaecf0;font-weight:700}tbody th{background:#f8f9fa;width:24%;font-weight:650}.card-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:1.25rem 1.5rem;margin:1.1rem 0;padding:0;list-style:none;display:grid}.card-grid>li{min-width:0;margin:0}.info-card{border-top:2px solid var(--line);height:100%;padding:.75rem 0}.info-card h2,.info-card h3{margin:0 0 .35rem;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;font-size:1rem;font-weight:700;line-height:1.35}.info-card p{color:var(--ink-soft);margin:0;font-size:.87rem;line-height:1.5}.card-action{margin-top:.5rem;font-size:.82rem;font-weight:650;display:inline-block}.editorial-figure{border:1px solid var(--line-light);background:var(--surface);margin:1.5rem 0;padding:.7rem}.editorial-figure img{width:auto;max-height:43rem;margin-inline:auto;display:block}.diagram-figure img{width:100%}.editorial-figure figcaption{border-top:1px solid var(--line-light);color:var(--muted);margin-top:.65rem;padding-top:.55rem;font-size:.76rem;line-height:1.45}.figure-caption,.figure-credit{display:block}.figure-caption{color:var(--ink-soft);font-size:.83rem}.figure-credit{margin-top:.25rem}.faq-category{margin-top:1.8rem}.faq-list{border-top:1px solid var(--line)}.faq-list details,.quiz-answer-key details{border-bottom:1px solid var(--line-light);background:0 0}.faq-list summary,.quiz-answer-key summary{cursor:pointer;padding:.68rem 2rem .68rem 0;font-weight:650;line-height:1.4}.faq-list details[open] summary,.quiz-answer-key details[open] summary{color:var(--accent)}.faq-list details p,.quiz-answer-key details p{margin:0;padding:0 0 .85rem}.source-list{margin:0;padding-left:2.2rem}.source-list>li{border-bottom:1px solid var(--line-light);margin-bottom:1rem;padding:0 0 .9rem .25rem}.source-list p{margin:.2rem 0;font-size:.86rem;line-height:1.48}.source-citation{color:var(--ink)}.source-note{color:var(--muted)}.source-link{font-size:.78rem!important}.further-watching{border-top:3px double var(--line);border-bottom:3px double var(--line);margin:2.5rem 0;padding:1rem 0}.further-watching h2{border:0}.channel-link{font-weight:700}.revision-history{color:var(--muted);margin-top:2.2rem;font-size:.78rem}.revision-history h2{font-size:1.15rem}.revision-history ul{padding-left:1.2rem}.quiz-block{margin:2.5rem 0}.quiz-block fieldset{border:1px solid var(--line);background:var(--surface);margin:0 0 1.1rem;padding:.9rem}.quiz-block fieldset.is-correct{border-left:5px solid #287a45}.quiz-block fieldset.is-incorrect{border-left:5px solid #a23a32}.quiz-block legend{padding-inline:.25rem;font-weight:700}.quiz-options{gap:.35rem;display:grid}.quiz-options label{cursor:pointer;grid-template-columns:auto 1fr;align-items:start;gap:.55rem;padding:.45rem .55rem;display:grid}.quiz-options label:hover{background:var(--surface-muted)}.quiz-options input{width:1.05rem;height:1.05rem;margin-top:.25rem}.quiz-block button{border:2px solid var(--accent);color:#fff;background:var(--accent);cursor:pointer;padding:.52rem .9rem;font-weight:700}.quiz-block button:hover{color:var(--accent);background:var(--surface)}.quiz-result{min-height:1.6rem;margin-top:.7rem;font-weight:700;display:block}.quiz-answer-key{margin-top:1.4rem}.quiz-answer-key>h3{margin-bottom:.2rem}.no-script-note{color:var(--muted);font-size:.82rem}.print-only{display:none}.site-footer{border-top:1px solid var(--line);background:#eaecf0}.footer-inner{width:min(calc(100% - 2rem), var(--site-max));grid-template-columns:minmax(18rem,2.2fr) repeat(3,minmax(9rem,1fr));gap:2.5rem;margin-inline:auto;padding-block:2.5rem 2rem;display:grid}.footer-brand{color:var(--ink);font-family:Georgia,Times New Roman,Times,serif;font-size:1.2rem;font-weight:700;text-decoration:none}.footer-about p{max-width:45ch;color:var(--ink-soft);margin:.45rem 0;font-size:.82rem;line-height:1.5}.footer-about .safety-note{color:var(--muted);font-size:.72rem}.footer-nav{flex-direction:column;align-items:flex-start;gap:.35rem;display:flex}.footer-nav h2{letter-spacing:.06em;text-transform:uppercase;margin:0 0 .35rem;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif;font-size:.74rem;font-weight:750}.footer-nav a{font-size:.8rem}.footer-colophon{border-top:1px solid var(--line-light)}.footer-colophon p{width:min(calc(100% - 2rem), var(--site-max));color:var(--muted);margin:0 auto;padding-block:.7rem;font-size:.7rem}.blog-reference-grid .article-body{grid-column:2}.blog-article>h2{margin-top:2.3rem}.blog-article>h3{margin-top:1.6rem}.blog-article>ul,.blog-article>ol{padding-left:1.35rem}.blog-article>table{border:1px solid var(--line);margin-block:1.2rem;display:block;overflow-x:auto}.blog-list{gap:1.2rem;margin-top:1.5rem;display:grid}.blog-list .info-card{padding-block:.9rem}@media (width<=74rem){:root{--left-rail:11rem;--right-rail:13rem;--grid-gap:1.5rem}.header-inner{align-items:flex-start;padding-block:.8rem}.brand{padding-top:.2rem}.primary-nav{max-width:38rem}}@media (width<=61rem){.article-header,.article>:not(.article-header,.reference-grid){margin-left:0}.reference-grid{grid-template-columns:minmax(0,1fr) minmax(12rem,15rem)}.contents-rail{scrollbar-gutter:auto;grid-column:1/-1;max-height:none;position:static;overflow:visible}.article-body,.blog-reference-grid .article-body{grid-column:1}.facts-rail{grid-column:2}.table-of-contents{border:1px solid var(--line-light);background:var(--surface);margin-bottom:.25rem;padding:.65rem .8rem;position:static}.table-of-contents ol{columns:3 12rem;column-gap:1.5rem}.table-of-contents li{break-inside:avoid}.footer-inner{grid-template-columns:minmax(18rem,2fr) repeat(2,minmax(9rem,1fr))}.footer-nav:last-child{grid-column:2/-1}}@media (width<=47.5rem){.header-inner{flex-wrap:wrap;align-items:center;min-height:4.25rem}.brand-copy small{display:none}.site-menu{margin-left:auto;display:block}.desktop-menu{display:none}.site-menu>summary{border:1px solid var(--line);cursor:pointer;padding:.38rem .65rem;font-size:.86rem;font-weight:700;list-style:none;display:block}.site-menu>summary::-webkit-details-marker{display:none}.site-menu>summary span:before{content:"☰";margin-right:.45rem}.site-menu[open]>summary span:before{content:"×"}.site-menu:not([open])>.site-menu-panel{display:none}.site-menu>.site-menu-panel{z-index:20;border:1px solid var(--line);background:var(--surface);align-items:stretch;padding:.9rem;position:absolute;top:4.5rem;left:1rem;right:1rem}.primary-nav,.resource-nav{grid-template-columns:repeat(2,minmax(0,1fr));justify-items:start;gap:.35rem 1rem;display:grid}.resource-nav{border-top:1px solid var(--line-light);padding-top:.7rem}.resource-nav>span{grid-column:1/-1}.page-shell{width:min(calc(100% - 1.25rem), var(--site-max));padding-bottom:3rem}.article-header{margin-top:1.5rem}.article h1{font-size:clamp(2rem,10vw,2.65rem)}.article-deck{font-size:.98rem}.reference-grid{display:block}.contents-rail{margin-bottom:1.5rem}.table-of-contents ol{columns:2 9rem}.facts-rail{margin-top:2rem}.quick-facts{position:static}.card-grid{grid-template-columns:1fr;gap:.6rem}.content-section>h2,.article-body>h2,.blog-article>h2,.quiz-block>h2,.further-watching>h2{font-size:1.45rem}.heading-anchor{opacity:1}.footer-inner{grid-template-columns:repeat(2,minmax(0,1fr));gap:2rem 1.25rem}.footer-about{grid-column:1/-1}.footer-nav:last-child{grid-column:auto}}@media (width<=31rem){.table-of-contents ol{columns:1}.primary-nav,.resource-nav{grid-template-columns:1fr}.resource-nav>span{grid-column:auto}.site-menu>.site-menu-panel{max-height:calc(100vh - 5.5rem);overflow-y:auto}.footer-inner{grid-template-columns:1fr}.footer-about,.footer-nav:last-child{grid-column:auto}}@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,:before,:after{scroll-behavior:auto!important;transition-duration:.01ms!important;animation-duration:.01ms!important;animation-iteration-count:1!important}}@media print{@page{margin:1.8cm}:root{--paper:#fff;--ink:#000}html{font-size:10.5pt}body{background:#fff}.site-header,.site-footer,.skip-link,.breadcrumbs,.contents-rail,.facts-rail,.heading-anchor,.related-section,.further-watching,.quiz-block form,.screen-only{display:none!important}.page-shell{width:100%;padding:0}.article-header,.article>:not(.article-header,.reference-grid){max-width:none;margin-left:0}.article-header{margin-top:0}.article h1{max-width:none;font-size:25pt}.reference-grid,.article-body,.blog-reference-grid .article-body{max-width:none;display:block}.content-section,.definition-box,.editorial-figure,blockquote,table,.faq-list details{break-inside:avoid}.print-only{display:block!important}.print-break-before{break-before:page}.table-wrap,.editorial-figure,.definition-box{background:#fff;border-color:#777}table{min-width:0;font-size:8.5pt}a{color:#000}}
