:root{--ink:#242424;--heading:#17202e;--muted:#686868;--line:#dedede;--blue:#244fdb;--pale:#f2f3f4;--paper:#fff;--sans:Arial,Helvetica,sans-serif}
*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:28px}body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--sans);font-size:18px;line-height:1.6;-webkit-font-smoothing:antialiased}a{color:inherit;text-decoration-thickness:1px;text-underline-offset:3px}a:hover{text-decoration-thickness:2px}button,input,select,textarea{font:inherit}a:focus-visible,button:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible,textarea:focus-visible{outline:2px solid var(--blue);outline-offset:5px}p{margin:0 0 1.25em}h1,h2,h3,h4{color:var(--heading);font-weight:600;line-height:1.25;margin:0}h1{font-size:2.5rem;letter-spacing:-.035em}h2{font-size:1.9rem;letter-spacing:-.025em}h3{font-size:1.4rem;letter-spacing:-.015em}strong{font-weight:600}img{max-width:100%}ul,ol{padding-left:1.4em;margin:1.1em 0 1.5em}li{padding-left:.15em;margin-bottom:.6em}::selection{background:#e1e8f4}[hidden]{display:none!important}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.skip{position:absolute;top:-100px;left:20px;background:#242424;color:white;padding:12px;z-index:20}.skip:focus{top:12px}.reading-progress{position:fixed;top:0;left:0;width:0;height:2px;background:#777;z-index:30}
.site-header,.page-shell,.site-footer{padding-left:max(6vw,24px);padding-right:max(6vw,24px)}.header-inner{max-width:1200px;margin:auto;min-height:118px;display:flex;align-items:center;justify-content:space-between;gap:28px}.wordmark{text-decoration:none;font-size:1.7rem;font-weight:600;letter-spacing:-.055em;white-space:nowrap;color:#171717}.wordmark b{font-weight:600;margin-left:4px}.nav{display:flex;gap:26px;align-items:center;font-size:.9375rem}.nav a{text-decoration:none;padding:10px 0}.nav a:hover,.nav a[aria-current=page]{text-decoration:underline;text-underline-offset:6px}.course-search{max-width:1200px;margin:20px auto 0;display:flex;align-items:center;gap:14px;border-bottom:1px solid #454545;padding:12px 0 20px}.course-search svg{width:22px;height:22px;color:#777;flex-shrink:0}.course-search input{width:100%;border:0;background:white;color:var(--ink);font-size:1.125rem;min-width:0;padding:8px 0}.course-search input:focus{outline:none}.course-search:focus-within{outline:2px solid var(--blue);outline-offset:6px}.course-search button{border:0;border-radius:6px;background:var(--blue);padding:9px 15px;cursor:pointer;font-size:.875rem;color:#fff}.course-search button:hover{background:#1c3faf}.course-strip{max-width:1200px;margin:0 auto;padding:16px 0 0;font-size:.875rem;color:var(--muted);display:flex;justify-content:space-between;gap:20px}.course-strip p{margin:0}.course-strip .facts{display:flex;gap:20px}.reader-layout{max-width:1200px;margin:64px auto 96px;display:grid;grid-template-columns:minmax(0,780px) 260px;gap:80px;align-items:start}.reader-layout article{min-width:0}.breadcrumbs{display:flex;align-items:center;flex-wrap:wrap;gap:8px;font-size:.875rem;color:var(--muted);margin-bottom:30px}.breadcrumbs a{text-decoration:none}.breadcrumbs a:hover{text-decoration:underline}.breadcrumbs .divider{color:#999}.article-header h1{margin-bottom:20px}.article-deck{font-size:1.125rem;color:var(--muted);line-height:1.55;margin-bottom:20px}.article-meta{display:flex;gap:10px;flex-wrap:wrap;color:#767676;font-size:.875rem;margin-bottom:32px}.article-meta span+span:before{content:'·';padding-right:10px}.learning-goal{margin-bottom:42px}.learning-goal span{font-size:.9375rem;font-weight:600;display:block;margin-bottom:8px}.learning-goal p{margin:0;font-size:1.125rem;line-height:1.65}.lesson-section{margin-bottom:46px;scroll-margin-top:32px}.lesson-section h2{margin:0 0 24px}.lesson-section h3{margin:30px 0 16px}.lesson-section h4{font-size:1.1rem;margin:24px 0 12px}.lesson-section p,.lesson-section li{font-size:1.125rem;line-height:1.65}.lesson-section p:last-child{margin-bottom:0}.lesson-section blockquote{margin:26px 0;padding:0 0 0 22px;border-left:2px solid #d0d0d0}.lesson-section blockquote p{font:inherit}.lesson-section em{font-style:normal;color:var(--muted)}.lesson-section code{background:#f5f5f5;padding:2px 4px;border-radius:3px}.table-wrap{overflow-x:auto;margin:26px 0;border:1px solid #d3d5d7;border-radius:10px}.lesson-section table{border-collapse:separate;border-spacing:0;font-size:1rem;min-width:450px;width:100%;line-height:1.5}.lesson-section th,.lesson-section td{text-align:left;border-bottom:1px solid #d3d5d7;border-right:1px solid #d3d5d7;padding:13px 16px;vertical-align:top}.lesson-section th{background:#e9ecef;font-weight:600}.lesson-section th:last-child,.lesson-section td:last-child{border-right:0}.lesson-section tr:last-child td{border-bottom:0}.exercise{padding:30px 0 0;border-top:1px solid var(--line)}.answer{border:1px solid #d6d6d6;border-radius:10px;background:#fff}.answer>summary{cursor:pointer;list-style:none;font-size:1.25rem;font-weight:600;padding:22px 24px;display:flex;align-items:center;justify-content:space-between;gap:20px}.answer>summary:after{content:'+';font-size:1.5rem;font-weight:400;color:var(--muted)}.answer[open]>summary:after{content:'−'}.answer>summary::-webkit-details-marker{display:none}.answer-body{padding:4px 24px 26px}.takeaway{padding-top:8px}.sources{border-top:1px solid var(--line);padding-top:26px;color:var(--muted);font-size:.9375rem}.sources h2{font-size:1.125rem;letter-spacing:0;margin:0 0 14px}.sources ul{margin-bottom:0}.sources li{line-height:1.6}.lesson-pagination{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin-top:42px}.lesson-pagination>div{border:1px solid #d6d6d6;border-radius:12px;padding:22px;min-width:0}.lesson-pagination span{display:block;font-size:.875rem;color:var(--muted);margin-bottom:9px}.lesson-pagination a{text-decoration:none;line-height:1.5;font-size:1rem}.lesson-pagination a:hover{text-decoration:underline}.lesson-pagination p{font-size:1rem;line-height:1.5;margin:0}.lesson-pagination small{font-size:.875rem;color:var(--muted)}.lesson-aside{position:sticky;top:32px;padding-top:61px;align-self:start;color:var(--muted);font-size:.9375rem}.toc-disclosure>summary{list-style:none;font-size:.875rem;color:var(--muted);margin-bottom:12px;pointer-events:none}.toc-disclosure>summary::-webkit-details-marker{display:none}.toc a{display:block;text-decoration:none;line-height:1.45;padding:7px 0;color:#626262}.toc a:hover,.toc a[aria-current=location]{color:#222}.toc a[aria-current=location]{font-weight:600}.aside-module{margin-top:28px;padding-top:20px;border-top:1px solid #eee;line-height:1.5;font-size:.875rem}.aside-module span{display:block;margin-bottom:5px}.start-link{display:inline-block;font-size:.875rem;margin-top:16px}
.index-page{max-width:1200px;margin:60px auto 90px}.eyebrow{font-size:.875rem;color:var(--muted);letter-spacing:0;text-transform:none;margin-bottom:12px}.index-intro{display:grid;grid-template-columns:minmax(0,760px) 260px;gap:80px;margin-bottom:38px;align-items:start}.index-intro h1{margin:0 0 20px}.index-intro p{color:var(--muted);max-width:720px;margin:0}.course-count{font-size:.9375rem;color:var(--muted);padding-top:8px}.course-count strong{display:block;color:var(--ink);font-size:1.125rem;margin-bottom:8px}.course-count a{display:inline-block;margin-top:12px}.search-bar{display:flex;gap:24px;margin:28px 0;align-items:flex-end}.search-field{flex:1;position:relative}.search-field label,.filter-field label{display:block;font-size:.875rem;color:var(--muted);margin-bottom:8px}.search-field input{width:100%;padding:13px 45px 13px 0;border:0;border-bottom:1px solid #777;background:#fff;color:var(--ink);min-height:50px}.filter-field select{border:1px solid #ccc;padding:12px;border-radius:6px;max-width:320px;min-height:50px;background:white;color:var(--ink);font-size:1rem}.clear-search{position:absolute;right:8px;bottom:8px;border:0;background:none;padding:2px 8px;font-size:24px;cursor:pointer;color:#777}.results-caption{display:flex;justify-content:space-between;gap:16px;color:var(--muted);font-size:.875rem;margin:20px 0 24px}.archive-list{list-style:none;padding:0;margin:0}.archive-card{border:1px solid #d6d6d6;border-radius:12px;display:grid;grid-template-columns:48px minmax(0,1fr) 105px;gap:22px;padding:28px;margin-bottom:18px}.archive-number{font-size:1rem;color:var(--muted);padding-top:3px;font-variant-numeric:tabular-nums}.archive-card .eyebrow{font-size:.875rem;margin-bottom:10px}.archive-card h2{font-size:1.375rem;letter-spacing:-.01em;line-height:1.4;margin:0 0 8px}.archive-card h2 a{text-decoration:none}.archive-card h2 a:hover{text-decoration:underline}.archive-card p{font-size:1rem;color:var(--muted);line-height:1.55;margin:0;max-width:720px}.archive-date{font-size:.875rem;color:var(--muted);text-align:right;line-height:1.7}.empty-state{border:1px solid var(--line);border-radius:12px;padding:35px;color:var(--muted)}.empty-state h2{font-size:1.5rem;margin-bottom:12px}.empty-state p{margin:0}.module{border-top:1px solid var(--line)}.module:last-of-type{border-bottom:1px solid var(--line)}.module>summary{display:grid;grid-template-columns:40px 1fr 20px;gap:20px;align-items:center;padding:26px 0;cursor:pointer;list-style:none}.module>summary::-webkit-details-marker{display:none}.module-number{font-size:.9375rem;color:var(--muted)}.module>summary h2{font-size:1.375rem;letter-spacing:-.01em}.module>summary small{display:block;color:var(--muted);font-size:.875rem;margin-top:8px}.module-toggle{color:#666;font-size:1.5rem}.module-toggle:before{content:'+'}.module[open] .module-toggle:before{content:'−'}.module-content{margin:0 40px 28px 60px}.module-outcome{color:var(--muted);font-size:1rem;max-width:750px;margin-bottom:24px}.syllabus-list{list-style:none;padding:0;margin:0}.syllabus-row{display:grid;grid-template-columns:40px 1fr 90px;gap:16px;border-top:1px solid #eee;padding:20px 0}.syllabus-row>span:first-child{font-size:.875rem;color:var(--muted);padding-top:3px}.syllabus-row h3{font-size:1.0625rem;font-weight:500;line-height:1.5;letter-spacing:0}.syllabus-row p{font-size:.9375rem;color:var(--muted);line-height:1.6;margin:6px 0 0}.syllabus-row .status{font-size:.875rem;line-height:1.5;text-align:right;color:var(--muted);padding-top:3px}.syllabus-row .available{color:#343434}.site-footer{border-top:1px solid var(--line);padding-top:32px;padding-bottom:36px}.footer-inner{max-width:1200px;margin:auto;display:flex;justify-content:space-between;align-items:center;gap:24px}.footer-brand{font-size:1.0625rem;font-weight:600;letter-spacing:-.02em}.footer-links{display:flex;gap:24px;font-size:.875rem;color:var(--muted)}.error-page{max-width:740px;margin:100px auto}.error-page h1{margin:20px 0}.error-page p{color:var(--muted)}
/* Functional accents: shared with the Post comment button. */
.reading-progress{background:var(--blue)}
.nav a:hover,.nav a[aria-current=page]{color:var(--blue)}
.breadcrumbs a,.lesson-section a,.sources a,.lesson-pagination a,.start-link,.course-count a,.syllabus-row h3 a,.footer-links a,.error-page a{color:var(--blue)}
.archive-card h2 a{color:var(--blue)}
.toc a{border-left:2px solid transparent;padding-left:12px}
.toc a:hover{color:var(--blue)}
.toc a[aria-current=location]{color:var(--blue);border-left-color:var(--blue)}
.answer>summary:after,.module-toggle,.toc-disclosure>summary:after{color:var(--blue)}
.answer>summary:hover,.module>summary:hover h2{color:var(--blue)}
.search-field input:focus{border-bottom-color:var(--blue)}
.course-search:focus-within svg{color:var(--blue)}
@media(max-width:1100px){.reader-layout{grid-template-columns:minmax(0,1fr) 220px;gap:48px}.index-intro{grid-template-columns:1fr 220px;gap:40px}.article-header h1{font-size:2.25rem}}
@media(max-width:800px){.site-header,.page-shell,.site-footer{padding-left:24px;padding-right:24px}.header-inner{min-height:110px;align-items:flex-start;justify-content:center;flex-direction:column;gap:10px;padding:24px 0}.wordmark{font-size:1.5rem}.nav{font-size:.875rem;gap:24px}.nav a{padding:6px 0}.course-search{margin-top:8px;padding-bottom:14px}.course-search input{font-size:1rem}.course-strip{font-size:.875rem}.course-strip .facts{display:none}.reader-layout{display:flex;flex-direction:column;gap:0;margin:30px auto 64px}.lesson-aside{order:-1;position:static;width:100%;padding:0;margin-bottom:30px}.toc-disclosure{border-bottom:1px solid var(--line);padding-bottom:16px}.toc-disclosure>summary{pointer-events:auto;cursor:pointer;display:flex;justify-content:space-between;align-items:center;font-size:.9375rem;margin:0;min-height:30px}.toc-disclosure>summary:after{content:'+';font-size:1.4rem}.toc-disclosure[open]>summary:after{content:'−'}.toc{padding-top:12px}.aside-module,.lesson-aside .start-link{display:none}.breadcrumbs{font-size:.875rem;margin-bottom:22px;gap:7px}.article-header h1{font-size:2rem;line-height:1.2}.article-deck{font-size:1.0625rem}.article-meta{font-size:.875rem;line-height:1.5;margin-bottom:28px}.learning-goal{margin-bottom:34px}.learning-goal p,.lesson-section p,.lesson-section li{font-size:1.0625rem;line-height:1.7}.lesson-section{margin-bottom:36px}.lesson-section h2{font-size:1.625rem;margin-bottom:20px}.lesson-section h3{font-size:1.25rem}.answer>summary{font-size:1.125rem;padding:20px}.answer-body{padding:2px 20px 22px}.lesson-pagination{gap:12px}.lesson-pagination>div{padding:18px}.index-page{margin:34px auto 65px}.index-intro{display:block;margin-bottom:30px}.index-intro h1{font-size:2rem}.index-intro p{font-size:1.0625rem}.course-count{margin-top:24px}.course-count strong{display:inline;margin-right:8px}.course-count a{margin-top:8px}.search-bar{display:block}.filter-field{margin-top:18px}.filter-field select{width:100%;max-width:none}.search-field input{font-size:1rem}.archive-card{grid-template-columns:36px 1fr;gap:14px;padding:22px 18px}.archive-card h2{font-size:1.25rem}.archive-card .eyebrow{font-size:.875rem}.archive-date{grid-column:2;text-align:left}.archive-date br{display:none}.archive-date span{margin-left:10px}.module>summary{grid-template-columns:26px 1fr 16px;gap:12px}.module>summary h2{font-size:1.25rem}.module-content{margin-left:0;margin-right:0}.syllabus-row{grid-template-columns:30px 1fr;gap:12px}.syllabus-row .status{grid-column:2;text-align:left;padding:0}.footer-inner{display:block}.footer-links{margin-top:16px;flex-wrap:wrap;gap:16px}.results-caption{flex-wrap:wrap}.error-page{margin:64px auto}}
@media(max-width:420px){.site-header,.page-shell,.site-footer{padding-left:20px;padding-right:20px}.article-header h1{font-size:1.875rem}.lesson-pagination{grid-template-columns:1fr}.nav{gap:20px}.course-search button{padding:9px 12px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
@media print{.site-header,.course-strip,.course-search,.lesson-aside,.site-footer,.lesson-pagination,.reading-progress,.discussion{display:none}.page-shell{padding:0}.reader-layout{display:block;max-width:none;margin:0}.article-header h1{font-size:26pt}.article-deck{font-size:12pt}.lesson-section p,.lesson-section li{font-size:11pt}.lesson-section h2{font-size:19pt}.answer:not([open])>.answer-body{display:block}.lesson-section{break-inside:avoid-page}}

/* Lesson discussion */
.discussion{margin-top:3.5rem;padding-top:2.5rem;border-top:2px solid var(--ink,#18202f)}
.discussion h2{font-size:2rem;margin:0 0 .65rem;letter-spacing:-.03em}
.discussion-intro{color:#4f5764;margin:0 0 1.6rem;line-height:1.65}
.comment-form,.reply-form{display:grid;gap:.6rem}
.comment-form label,.reply-form label{font-size:.875rem;font-weight:600}
.comment-form label span{font-weight:400;color:#657080}
.comment-form input,.comment-form textarea,.reply-form textarea{font:inherit;font-size:1rem;border:1px solid #c5cbd4;border-radius:5px;padding:.8rem;background:#fff;width:100%;color:#17202d;box-sizing:border-box}
.comment-form input{max-width:340px;margin-bottom:.5rem}
.comment-form textarea,.reply-form textarea{resize:vertical;min-height:125px;line-height:1.55}
.comment-form input:focus,.comment-form textarea:focus,.reply-form textarea:focus{outline:2px solid #244fdb;outline-offset:2px}
.comment-honeypot{position:absolute!important;left:-10000px!important;width:1px;height:1px;overflow:hidden}
.comment-form-note{font-size:.875rem;color:#616b79;margin:.1rem 0 .4rem;line-height:1.6}
.comment-submit{justify-self:start;background:#244fdb;color:white;border:1px solid #244fdb;border-radius:5px;font:inherit;font-size:.9375rem;font-weight:600;padding:.8rem 1.15rem;cursor:pointer;min-height:44px}
.comment-submit:hover{background:#1c3faf}
.discussion button:disabled{opacity:.6;cursor:wait}
.discussion button:focus-visible,.discussion a:focus-visible{outline:2px solid #244fdb;outline-offset:3px}
.comments-toolbar{display:flex;align-items:center;justify-content:space-between;gap:1rem;flex-wrap:wrap;margin-top:2rem;padding-bottom:1rem;border-bottom:1px solid #dce0e5;font-size:.875rem;color:#586372}
.comments-toolbar strong{color:#18202f}
.comment-status{font-size:.9375rem;margin:.9rem 0;line-height:1.5}
.comment-error,.comment-feedback{color:#a11b28}
.comment-feedback:empty,.comment-status:empty{display:none}
.comment-feedback{font-size:.875rem;margin:.6rem 0 0}
.comments-empty{padding:1.1rem 0;color:#657080;font-size:1rem}
.comment-thread{padding:1.5rem 0;border-bottom:1px solid #dce0e5}
.comment-meta{display:flex;align-items:center;gap:.6rem .8rem;flex-wrap:wrap;font-size:.875rem}
.comment-meta strong{font-size:1rem;overflow-wrap:anywhere}
.comment-meta time{color:#66717e;font-size:.8125rem}
.owner-badge{font-size:.75rem;color:#244fdb;background:#edf2ff;border-radius:3px;padding:.18rem .4rem;font-weight:600}
.comment-body{white-space:pre-wrap;overflow-wrap:anywhere;line-height:1.65;font-size:1rem;margin:.75rem 0 1rem}
.comment-votes{display:flex;gap:.75rem;flex-wrap:wrap}
.vote{display:inline-flex;align-items:center;gap:.25rem;background:transparent;color:#244fdb;border:0;border-radius:0;min-height:28px;padding:.125rem 0;font:inherit;font-size:.875rem;cursor:pointer}
.vote-icon{width:18px;height:18px;fill:none;stroke:currentColor;stroke-width:1.8;stroke-linejoin:round}
.vote-disagree .vote-icon{transform:rotate(180deg)}
.vote-count{font-variant-numeric:tabular-nums;font-weight:600;min-width:.6rem}
.vote[aria-pressed=true] .vote-icon{fill:currentColor}
.vote:hover{color:#1c3faf}
.vote:focus-visible{outline:2px solid #244fdb;outline-offset:3px}
.comment-reply{margin:1.3rem 0 0 1rem;padding:0 0 0 1.1rem;border-left:2px solid #dbe4fb}
.comment-owner-controls{display:flex;gap:1rem;margin-top:.8rem}
.text-button{font:inherit;font-size:.875rem;background:transparent;border:0;padding:.35rem 0;color:#244fdb;text-decoration:underline;cursor:pointer;min-height:36px;text-underline-offset:3px}
.remove-comment{color:#a11b28}.reply-form{margin-top:1rem}.reply-form .text-button{justify-self:start}
.comment-auth{font-size:.8125rem;color:#66717e;margin-top:1.5rem}.comment-auth a{color:#485977;text-underline-offset:3px}
.comments-more{margin-top:1.25rem}
@media(max-width:480px){.discussion{margin-top:2.5rem;padding-top:2rem}.comment-reply{margin-left:.3rem;padding-left:.8rem}}

.discussion{border-top:1px solid var(--line)}.discussion h2{font-size:1.75rem;letter-spacing:-.02em;margin-bottom:24px}.comment-form input,.comment-form textarea,.reply-form textarea{border-color:#ccc;border-radius:8px;color:var(--ink)}.comments-toolbar,.comment-meta time,.comments-empty{color:var(--muted)}