:has(>.learn-cards){container:learn-cards/inline-size}.learn-cards{grid-template-columns:repeat(2,minmax(0,1fr));gap:18px;margin:0;padding:0;list-style:none;display:grid}.learn-cards>li{grid-area:span 4/span 2;grid-template-rows:subgrid;row-gap:0;display:grid}@container learn-cards (698px<=width<1056px){.learn-cards{grid-template-columns:repeat(4,minmax(0,1fr))}.learn-cards>li:nth-child(odd):last-child{grid-column:2/span 2}}@container learn-cards (width>=1056px){.learn-cards{grid-template-columns:repeat(6,minmax(0,1fr))}.learn-cards>li:nth-child(3n+1):last-child{grid-column:3/span 2}.learn-cards>li:nth-child(3n+1):nth-last-child(2){grid-column:2/span 2}}.learn-card{border:1.5px solid var(--line-strong);border-radius:var(--radius-lg);box-shadow:0 2px 0 var(--line-strong);background:#fff;padding:23px}.learn-card :is(h2,h3,h4){font-size:var(--fs-2xl);line-height:var(--lh-heading);letter-spacing:var(--track-heading);margin:0 0 12px;font-weight:800}.learn-card :is(h2,h3,h4) a{color:var(--ink)}.learn-card>p:not(.article-kicker){font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--muted);margin:0 0 14px}.learn-card--link{transition:border-color .15s,box-shadow .15s,transform .1s;position:relative}.learn-card--link :is(h2,h3,h4) a:after{content:"";border-radius:var(--radius-lg);position:absolute;inset:0}.learn-card--link :is(h2,h3,h4) a:focus-visible{outline:none}.learn-card--link:hover{border-color:var(--brand);box-shadow:0 2px 0 var(--brand)}.learn-card--link:active{box-shadow:0 0 0 var(--brand);transform:translateY(2px)}.learn-card--link:hover :is(h2,h3,h4) a{color:var(--brand);text-decoration:none}.learn-card--link:has(:is(h2,h3,h4) a:focus-visible){outline:3px solid var(--brand);outline-offset:5px}.learn-card__foot{border-top:1.5px solid var(--line);justify-content:space-between;align-items:end;gap:16px;padding-top:14px;display:flex}.learn-card__units{min-width:0;overflow:hidden}.learn-card__units ul{margin:0;font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--ink);flex-wrap:wrap;margin-inline-start:-1em;padding:0;list-style:none;display:flex}.learn-card__units li{min-width:0}.learn-card__units li:before{content:"·" / "";text-align:center;width:1em;color:var(--muted);display:inline-block}.learn-card__more{vertical-align:middle;white-space:nowrap;font-size:var(--fs-xs);line-height:var(--lh-ui);color:var(--muted);margin-inline-start:.6em;display:inline-block}.learn-card__go{color:var(--brand);font-size:var(--fs-lg);font-weight:700;line-height:var(--lh-ui);flex:none}.learn-cards>li.learn-card--compact,.learn-cards>li[data-unit]{grid-row:span 3}.learn-card--compact .learn-card__foot{border-top:0;align-items:baseline;padding-top:0}.learn-card__line{white-space:nowrap;text-overflow:ellipsis;min-width:0;font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--muted);margin:0;overflow:hidden}.learn-card__progress:not([hidden]):before{content:" · "}.article-kicker:has(>.learn-card__progress:not([hidden]))>.learn-card__count{display:none}.learn-card__progress{color:var(--brand-dark)}.learn-shell>section{padding-bottom:56px}.learn-units{padding-top:16px}.learn-shell>.learn-cards{margin-bottom:56px}.lesson-mark{color:var(--brand);font-weight:800;line-height:var(--lh-ui);justify-self:end}.lesson-mark[hidden]{display:none}.lesson-mark[data-state=done]:before{content:"✓" / ""}.lesson-mark[data-state=started]:before{content:"";border:1.5px solid var(--brand);background:linear-gradient(90deg, var(--brand) 50%, transparent 50%);vertical-align:middle;border-radius:50%;width:9px;height:9px;display:inline-block}[dir=rtl] .lesson-mark[data-state=started]:before{background:linear-gradient(-90deg, var(--brand) 50%, transparent 50%)}.learn-lessons{border-top:1.5px solid var(--line);margin:0;padding:0;list-style:none}.learn-lesson{isolation:isolate;grid-template-columns:minmax(0, 1fr) var(--row-meta) 32px;border-bottom:1.5px solid var(--line);align-items:baseline;column-gap:0;padding:22px 0;display:grid;position:relative}.learn-lesson>div{grid-area:1/1;padding-inline:46px 24px}.learn-lesson:before{content:"";z-index:-1;border-radius:var(--radius);background:var(--tint);opacity:0;transition:opacity .15s;position:absolute;inset:0 -12px}.learn-lesson:hover:before{opacity:1}.learn-lesson h3 a:after{content:"";position:absolute;inset:0}.learn-lesson h3 a:focus-visible{outline:none}.learn-lesson:has(h3 a:focus-visible){outline:3px solid var(--brand);outline-offset:2px}.learn-lesson:hover h3 a{color:var(--brand);text-decoration:none}.learn-lesson h3 a{transition:color .15s}.learn-lesson__number{inset-inline-start:0;font-family:var(--mono);color:var(--brand);font-size:var(--fs-xs);line-height:var(--lh-heading);padding-top:5px;position:absolute;top:22px}.learn-lesson h3{font-size:var(--fs-xl);line-height:var(--lh-heading);letter-spacing:var(--track-title);margin:0 0 8px;font-weight:800}.learn-lesson h3 a{color:var(--ink)}.learn-lesson p{max-width:640px;font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--muted);margin:0 0 6px}.learn-lesson p.learn-lesson__meta{text-align:end;font-size:var(--fs-xs);line-height:var(--lh-ui);flex-wrap:wrap;grid-area:1/2;justify-content:flex-end;align-items:baseline;gap:4px 16px;margin:0;display:flex}.learn-lesson__go{font-size:var(--fs-lg);font-weight:700;line-height:var(--lh-heading);color:var(--brand);grid-area:1/3;justify-self:end}.learn-before{border-top:1.5px solid var(--line);border-bottom:1.5px solid var(--line);grid-template-columns:auto minmax(0,1fr);align-items:center;gap:0 28px;margin-top:30px;padding:4px 0;display:grid}.learn-before .article-kicker{color:var(--muted);margin:0}.learn-before ul{margin:0;clip-path:inset(-8px -8px -8px 28px);flex-wrap:wrap;gap:0;margin-inline-start:-28px;padding:0;list-style:none;display:flex}[dir=rtl] .learn-before ul{clip-path:inset(-8px 28px -8px -8px)}.learn-before li:before{content:"·" / "";text-align:center;width:28px;color:var(--muted);align-self:center;margin-inline-end:-8px;font-weight:700;display:inline-block}.learn-before li{font-size:var(--fs-sm);line-height:var(--lh-ui);align-items:baseline;gap:8px;display:flex}.learn-before li a{align-items:center;min-height:44px;font-weight:700;display:inline-flex}.learn-before li span{font-size:var(--fs-xs);color:var(--muted)}@media (width<=767px){.learn-before{grid-template-columns:minmax(0,1fr);margin-top:36px;padding:12px 0 4px}.learn-before ul{flex-direction:column;margin-inline-start:0}.learn-before ul,[dir=rtl] .learn-before ul{clip-path:none}.learn-before li:before{content:none}.learn-before li{border-top:1.5px solid var(--line)}.learn-before .article-kicker{margin-bottom:6px}}.learn-syllabus{padding-top:0}.learn-next{border-top:1.5px solid var(--line);margin:0 0 56px}.learn-next a{flex-wrap:wrap;align-items:center;gap:4px 28px;min-height:44px;padding:10px 0;text-decoration:none;display:flex}.learn-next .article-kicker{color:var(--muted);margin:0}.learn-next__title{font-size:var(--fs-md);font-weight:700;line-height:var(--lh-ui);color:var(--brand)}.learn-next a:hover .learn-next__title{text-decoration:underline}.learn-syllabus h2{font-size:var(--fs-xl);letter-spacing:var(--track-title);margin:0 0 10px}.learn-syllabus p,.learn-syllabus li{font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--muted)}.learn-draft,.article-intro>.learn-draft{max-width:405px;font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--muted);background:var(--paper-dark);border-inline-start:3px solid var(--line-strong);margin:18px 0 0;padding:20px}.learn-hero h1{font-size:var(--fs-display-compact)}.learn-hero--index{padding-bottom:56px}.learn-hero--index .article-intro>p:last-child{margin-bottom:0}.learn-cards>li[id]{scroll-margin-top:24px}.learn-unit-index{margin-bottom:20px}.learn-unit-index:not(.learn-unit-index--grouped){display:block}.learn-unit-index__group{border-top:1.5px solid var(--line-strong);font-size:var(--fs-2xs);letter-spacing:var(--track-caps);text-transform:uppercase;color:var(--muted);margin:8px 0 0;padding:12px 0 6px;font-weight:700}.learn-unit-index__group+ol>li:first-child>a{border-top:0}.learn-group-nav{margin:0 0 40px}.learn-group-nav ol{grid-template-columns:repeat(auto-fill,minmax(min(100%,340px),1fr));column-gap:24px;margin:0;padding:0;list-style:none;display:grid}.learn-group-nav a{border-top:1.5px solid var(--line-strong);min-height:44px;font-size:var(--fs-sm);font-weight:700;line-height:var(--lh-ui);color:var(--ink);align-items:baseline;gap:10px;padding:11px 0;display:flex}.learn-group-nav a:hover{color:var(--brand);text-decoration:none}.learn-group-nav__range{min-width:5ch;font-family:var(--mono);font-size:var(--fs-xs);color:var(--brand);flex:none;font-weight:400}#units-title{font-size:var(--fs-3xl)}.learn-group{scroll-margin-top:24px}.learn-group+.learn-group{margin-top:56px}.learn-group__head{border-top:1.5px solid var(--line-strong);flex-wrap:wrap;justify-content:space-between;align-items:baseline;gap:4px 24px;margin:0 0 18px;padding-top:16px;display:flex}.learn-group__head h3{font-size:var(--fs-2xl);line-height:var(--lh-heading);letter-spacing:var(--track-heading);margin:0;font-weight:800}.learn-group__head p{font-family:var(--mono);font-size:var(--fs-xs);color:var(--muted);margin:0}.learn-card .learn-card__title{font-size:var(--fs-xl);letter-spacing:var(--track-title);justify-content:space-between;align-items:baseline;gap:12px;display:flex}.learn-card__cue{flex:none;align-items:baseline;gap:10px;display:inline-flex}.learn-card__cue .lesson-mark{font-size:var(--fs-md)}.lesson-hero{padding-bottom:28px}.lesson-hero h1{font-size:var(--fs-display-compact)}.lesson-steps{border-top:1.5px solid var(--line);border-bottom:1.5px solid var(--line);padding:14px 0}.lesson-steps ol{grid-template-columns:repeat(var(--cols,5), minmax(0, 1fr));align-items:start;gap:4px 30px;margin:0;padding:0;list-style:none;display:grid}.lesson-steps a{color:var(--muted);font-size:var(--fs-xs);padding-block:4px;font-weight:700;display:inline-block}.lesson-steps a span{color:var(--brand);font-family:var(--mono);font-weight:400;font-size:var(--fs-xs);margin-inline-end:6px}.lesson-steps a .lesson-steps__check,.lesson-steps a .lesson-steps__check span{color:var(--brand-dark);font-family:inherit;font-weight:700;font-size:inherit;margin:0}.lesson-intro{padding-top:32px}.lesson-texts{padding-top:36px}.lesson-step{max-width:720px}@media (width>=1200px){.lesson-step{grid-template-columns:var(--split);column-gap:var(--split-gap);align-items:start;max-width:none;display:grid}.lesson-step>.lesson-jump{margin-top:-14px;display:block}}.lesson-step+.lesson-step{margin-top:48px}.is-stepped .lesson-step+.lesson-step,.lesson-step h2{margin-top:0}.lesson-step h2:focus{outline:none}.lesson-step .article-kicker{margin-bottom:10px}.learn-shell>.lesson-lab{padding-top:20px;padding-bottom:0}.lesson-work{max-width:720px;padding:24px 0 64px}.lesson-jump{font-size:var(--fs-xs);margin:0;font-weight:700;display:none}.lesson-jump a{align-items:center;gap:6px;min-height:44px;display:inline-flex}.lesson-step-work,.lesson-lab{scroll-margin-top:12px}.lesson-step-work+.lesson-step-work{margin-top:32px}.lesson-pager{grid-template-columns:auto minmax(0,1fr) auto;grid-template-areas:"back note next";align-items:center;gap:8px 12px;margin-top:24px;display:grid}.lesson-pager__back{grid-area:back}.lesson-pager__go{grid-area:next}.lesson-pager__await{font-size:var(--fs-xs);color:var(--muted);grid-area:note;justify-self:end;font-weight:600}.lesson-pager__short{display:none}.lesson-hero .article-intro{max-width:none}.lesson-hero .article-intro>p{font-size:var(--fs-md)}.lesson-done{background:var(--tint);border:1.5px solid var(--brand);border-radius:var(--radius);font-size:var(--fs-sm);color:var(--brand-dark);margin:24px 0 0;padding:14px 16px;font-weight:600}.lesson-left{border:1.5px solid var(--line);border-inline-start:3px solid var(--brand);border-radius:var(--radius);font-size:var(--fs-sm);background:#fff;margin:24px 0 0;padding:14px 16px}.lesson-left p{color:var(--ink);margin:0 0 8px;font-weight:600}.lesson-left ul{gap:6px;margin:0;padding:0;list-style:none;display:grid}.lesson-left a{font-weight:700}.lesson-left a span{color:var(--brand);font-family:var(--mono);font-weight:400;font-size:var(--fs-xs);margin-inline-end:6px}.lesson-done[hidden],.lesson-left[hidden],.lesson-left li[hidden],.lesson-step[hidden],.lesson-step-work[hidden]{display:none}.lesson-lab .control__locked{font-size:var(--fs-2xs);letter-spacing:var(--track-label);color:var(--muted);border:1px solid var(--control-edge);border-radius:var(--radius-sm);vertical-align:1px;margin-inline-start:8px;padding:2px 6px;font-weight:700;display:inline-block}.lesson-lab .hud-panel input[type=range]:disabled{opacity:.4;cursor:not-allowed}.lesson-lab .hud-panel button:disabled{opacity:.45;cursor:not-allowed}.lesson-lab .lab-observation{margin-top:4px}.practice{border:1.5px solid var(--line-strong);border-radius:var(--radius-lg);box-shadow:0 2px 0 var(--line-strong);background:#fff;padding:23px}.practice__label{margin:0}.practice__head{flex-wrap:wrap;justify-content:space-between;align-items:baseline;gap:8px 16px;display:flex}.practice__before{font-size:var(--fs-2xs);color:var(--brand-dark);font-weight:600}.practice__prompt{font-size:var(--fs-md);line-height:var(--lh-body);color:var(--ink)}.practice__prompt p{margin:0 0 16px}.practice__form{justify-items:start;gap:16px;display:grid}.practice fieldset{border:0;width:100%;min-width:0;margin:0;padding:0}.practice__note{font-size:var(--fs-xs);color:var(--muted);margin:0 0 8px}.practice__choices{gap:8px;display:grid}.practice__choice{border:1.5px solid var(--control-edge);border-radius:var(--radius);min-height:44px;font-size:var(--fs-sm);line-height:var(--lh-ui);cursor:pointer;background:#fff;align-items:center;gap:12px;padding:10px 12px;display:flex}.practice__choice:not(:has(input:disabled)):hover{border-color:var(--brand);background:var(--paper-hover)}.practice__choice:has(input:checked){border-color:var(--brand);background:var(--tint);box-shadow:inset 0 0 0 1.5px var(--brand);font-weight:700}.practice__choice:has(input:disabled){cursor:not-allowed;border-color:var(--line);color:var(--muted)}.practice__choice:has(input:disabled:checked){border-color:var(--brand);color:var(--ink)}.practice__number:disabled{color:var(--muted);background:var(--paper);border-color:var(--line);cursor:not-allowed}.practice__choice input{width:18px;height:18px;accent-color:var(--brand);flex:none;margin:0}.practice__answer{flex-wrap:wrap;align-items:center;gap:10px;display:flex}.practice__number,.practice__unit-picker select{height:44px;font-family:var(--mono);font-size:var(--fs-md);color:var(--ink);border:1.5px solid var(--control-edge);border-radius:var(--radius);background:#fff;padding:0 12px;font-weight:500}.practice__number{width:150px}.practice__number:focus-visible,.practice__unit-picker select:focus-visible{outline-offset:2px}.practice__unit{font-family:var(--mono);font-size:var(--fs-md);color:var(--muted);font-weight:500}.practice__goal{gap:6px;margin:0;display:grid}.practice__goal div{font-size:var(--fs-sm);grid-template-columns:auto auto;justify-content:start;gap:4px 14px;display:grid}.practice__goal dt{color:var(--muted);font-weight:600}.practice__goal dd{font-family:var(--mono);margin:0}.practice__feedback:empty{display:none}.practice__feedback{border-radius:var(--radius);border:1.5px solid var(--line);background:var(--paper);font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--ink);margin-top:18px;padding:14px 16px}.practice__feedback.is-correct{border-color:var(--brand);background:var(--tint)}.practice__feedback.is-wrong{border-color:var(--line-strong);background:var(--paper-dark)}.practice__feedback p{margin:0 0 8px}.practice__feedback p:last-child,.practice__html>:last-child{margin-bottom:0}.practice__verdict{font-weight:800}.practice__feedback.is-correct .practice__verdict{color:var(--brand-dark)}.practice__hint,.practice__solution{font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--muted);margin-top:16px}.practice__hint summary,.practice__solution summary{cursor:pointer;color:var(--brand);width:max-content;max-width:100%;font-weight:700;position:relative}.practice__hint summary:after,.practice__solution summary:after{content:"";inset-inline:-4px;position:absolute;top:calc(50% - 22px);bottom:calc(50% - 22px)}.practice__hint+.practice__solution{margin-top:20px}.practice__solution>:not(summary){color:var(--ink)}.practice__solution[open]{border:1.5px solid var(--line);border-radius:var(--radius);background:var(--paper);padding:12px 14px}.practice__solution p{margin:8px 0 0}.practice .math-display{display:block;overflow-x:auto}@media (width>=1051px){.lesson-work{max-width:none}.practice{grid-template-rows:auto auto auto auto auto 1fr;grid-template-columns:minmax(0,1fr) minmax(0,1fr);align-items:start;column-gap:48px;display:grid}.practice>*{grid-column:2}.practice>.practice__head{grid-area:1/1/auto/-1;margin-bottom:14px}.practice>.practice__prompt{grid-area:2/1/-1}.practice>.practice__prompt>:last-child{margin-bottom:0}.practice>.practice__feedback{margin-top:18px}.lesson-left,.lesson-done{max-width:720px}}.progress-jumps{margin-bottom:32px}.progress-jumps a[hidden]{display:none}.progress-jumps a span{margin:0;font-family:inherit;font-size:inherit;font-weight:inherit;letter-spacing:inherit;color:var(--brand);margin-inline-start:6px;display:inline}.progress-report{padding-bottom:56px}.progress-totals{grid-template-rows:auto auto auto;grid-template-columns:repeat(3,minmax(0,1fr));gap:0 18px;margin:0 0 36px;padding:0;list-style:none;display:grid}.progress-totals li{grid-row:span 3;grid-template-rows:subgrid;border:1.5px solid var(--line-strong);border-radius:var(--radius-lg);min-width:0;box-shadow:0 2px 0 var(--line-strong);background:#fff;row-gap:2px;padding:16px 20px 18px;display:grid}.progress-totals__bar{border-radius:var(--radius-sm);background:linear-gradient(to right, var(--brand) var(--done,0%), var(--line) var(--done,0%));grid-row:3;align-self:end;height:6px;margin-top:12px}[dir=rtl] .progress-totals__bar{background:linear-gradient(to left, var(--brand) var(--done,0%), var(--line) var(--done,0%))}.progress-empty{flex-wrap:wrap;justify-content:space-between;align-items:center;gap:14px 24px;margin:0 0 40px;display:flex}.progress-empty p{max-width:520px;font-size:var(--fs-sm);line-height:var(--lh-body);margin:0}.progress-hint{font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--muted);margin:0 0 40px}.progress-hint a{white-space:nowrap;font-weight:700}.progress-totals__label{font-size:var(--fs-sm);line-height:var(--lh-ui);color:var(--muted);grid-row:2}.progress-totals__figure{font-family:var(--mono);font-size:var(--fs-2xl);letter-spacing:var(--track-figure);font-weight:500;line-height:var(--lh-heading);text-align:start;color:var(--ink);grid-row:1}[dir=rtl] .progress-totals__figure{text-align:right}.progress-units>h2,.progress-misconceptions h2{font-size:var(--fs-2xl);letter-spacing:var(--track-heading);margin:0 0 14px}.progress-units{border-top:1.5px solid var(--line);margin-top:40px;padding-top:24px}.progress-units>.article-kicker{margin-bottom:10px}.progress-units>h2{margin-bottom:14px}.progress-key{font-size:var(--fs-xs);line-height:var(--lh-ui);color:var(--muted);flex-wrap:wrap;gap:6px 20px;margin:0 0 24px;padding:0;list-style:none;display:flex}.progress-key li{align-items:center;gap:6px;display:inline-flex}.progress-unit h3{font-size:var(--fs-xl);letter-spacing:var(--track-title);margin:0 0 14px}.progress-unit__head{grid-template-columns:var(--split);align-items:baseline;column-gap:var(--split-gap);display:grid}.progress-unit__head p{font-size:var(--fs-sm);color:var(--muted);margin:0 0 14px}.progress-unit h3 a{color:var(--ink)}.progress-lessons{border-top:1.5px solid var(--line);margin:0 0 40px;padding:0;list-style:none}.progress-lessons>li{border-bottom:1.5px solid var(--line);padding:14px 0 6px}.progress-lesson__head{grid-template-columns:var(--split);align-items:baseline;gap:4px var(--split-gap);display:grid}.progress-lessons h4{font-size:var(--fs-lg);letter-spacing:var(--track-title);margin:0}.progress-lessons h4 a{color:var(--ink)}.progress-lessons h4 a:hover{color:var(--brand);text-decoration:none}.progress-lessons h4 a>span{color:var(--brand);margin-inline-start:8px;font-weight:700}.progress-meter{font-size:var(--fs-sm);color:var(--muted);justify-content:start;align-items:center;gap:10px;margin:0;display:flex}.progress-meter__dots{gap:5px;display:flex}.progress-meter__dots span{border:1.5px solid var(--control-edge);background:#fff;border-radius:50%;width:11px;height:11px}.progress-meter__dots span[data-state=done]{background:var(--brand);border-color:var(--brand)}.progress-meter__dots span[data-state=tried]{background:linear-gradient(to right, var(--brand) 50%, #fff 50%);border-color:var(--brand)}.progress-lesson__items>summary{min-height:44px;font-size:var(--fs-xs);color:var(--brand);cursor:pointer;align-items:center;gap:8px;font-weight:700;list-style:none;display:inline-flex}.progress-lesson__items>summary::-webkit-details-marker{display:none}.progress-lesson__items>summary:after{content:"";border:solid var(--brand);border-width:0 2px 2px 0;width:6px;height:6px;transform:translateY(-2px)rotate(45deg)}.progress-lesson__items[open]>summary:after{transform:translateY(2px)rotate(-135deg)}.progress-items{font-size:var(--fs-sm);color:var(--muted);margin:0 0 10px;padding:0;list-style:none;display:grid}.progress-items li{grid-template-columns:var(--split);align-items:baseline;gap:2px var(--split-gap);border-top:1px solid var(--line);display:grid}.progress-items a{color:var(--ink);padding:10px 0;display:block}.progress-items li[data-state=none] a{color:var(--muted)}.progress-items li[data-state=done] .progress-item__state{color:var(--brand-dark);font-weight:700}.progress-items li[data-state=done] .progress-item__state:before{content:"✓ "}.progress-misconceptions{border-top:1.5px solid var(--line);margin:40px 0;padding-top:24px}.progress-misconceptions>.article-kicker{margin-bottom:10px}.progress-misconceptions ul{gap:14px;padding:0;list-style:none;display:grid}.progress-misconceptions li>a.article-kicker{margin-bottom:6px;display:inline-block}.progress-misconceptions li{border:1.5px solid var(--line-strong);border-radius:var(--radius-lg);font-size:var(--fs-sm);line-height:var(--lh-body);box-shadow:0 2px 0 var(--line-strong);background:#fff;padding:16px 18px}.progress-misconceptions p:not(.article-kicker){font-size:var(--fs-sm);color:var(--muted)}.progress-actions{flex-wrap:wrap;align-items:center;gap:12px;margin-top:16px;display:flex}.progress-backup{grid-template-columns:var(--split);align-items:start;column-gap:var(--split-gap);border-top:1.5px solid var(--line);margin-top:40px;padding-top:24px;display:grid}.progress-backup>*{grid-column:2}.progress-backup>.progress-backup__head{grid-area:1/1/span 4}.progress-backup__head .article-kicker{margin:0 0 10px}.progress-backup__head h2{font-size:var(--fs-2xl);letter-spacing:var(--track-heading);line-height:var(--lh-heading);margin:0 0 10px}.progress-backup>p{max-width:640px;font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--muted);margin:0}.progress-import{cursor:pointer}.progress-import:focus-within{outline:3px solid var(--brand);outline-offset:5px}.progress-note{min-height:1.5em;font-size:var(--fs-sm);color:var(--muted);margin:12px 0 0}.progress-not-started{margin:-16px 0 0;padding-bottom:16px}.progress-not-started>summary{min-height:44px;font-size:var(--fs-sm);color:var(--brand);cursor:pointer;align-items:center;gap:8px;font-weight:700;list-style:none;display:flex}.progress-not-started>summary::-webkit-details-marker{display:none}.progress-not-started>summary:after{content:"";border:solid var(--brand);border-width:0 2px 2px 0;width:6px;height:6px;transform:translateY(-2px)rotate(45deg)}.progress-not-started[open]>summary:after{transform:translateY(2px)rotate(-135deg)}.progress-not-started ul{columns:3 220px;font-size:var(--fs-sm);column-gap:30px;margin:0 0 14px;padding:0;list-style:none}.progress-not-started a{break-inside:avoid;padding:6px 0;display:block}.progress-confirm{border:1.5px solid var(--danger);border-radius:var(--radius);background:var(--danger-tint);max-width:640px;margin-top:16px;padding:14px 16px}.progress-confirm>p{font-size:var(--fs-sm);color:var(--ink);margin:0;font-weight:700}.progress-confirm>p:focus-visible{outline:3px solid var(--brand);outline-offset:4px;border-radius:var(--radius-sm)}.progress-confirm .progress-actions{margin-top:12px}.teacher-index{margin-bottom:36px}.teacher-tools{flex-wrap:wrap;align-items:center;gap:8px 24px;padding:10px 0;display:flex}.teacher-tools__link{min-height:44px;font-size:var(--fs-sm);align-items:center;font-weight:700;display:inline-flex}@media (width>=1051px){.teacher-layout{grid-template-columns:240px minmax(0,1fr);align-items:start;column-gap:64px;display:grid}.teacher-index{margin:0;max-height:calc(100vh - 32px);margin-inline-start:-12px;padding-inline:12px 8px;position:sticky;top:16px;overflow-y:auto}.teacher-toc{border-bottom:0;padding-top:10px}.teacher-tools{border-bottom:0;flex-direction:column;align-items:flex-start;gap:4px}}.teacher-toc{border-top:1.5px solid var(--line);border-bottom:1.5px solid var(--line);padding:18px 0}.teacher-toc>ol{grid-template-columns:repeat(auto-fill,minmax(240px,1fr));align-items:start;gap:18px 30px;margin:0;padding:0;list-style:none;display:grid}.teacher-toc__lesson{font-size:var(--fs-sm);line-height:var(--lh-ui);color:var(--ink);padding:7px 0;font-weight:700;display:block}.teacher-toc__lesson span{color:var(--brand);font-family:var(--mono);font-weight:400;font-size:var(--fs-xs);margin-inline-end:6px}.teacher-toc__steps{padding:0;border-inline-start:1.5px solid var(--line-strong);margin:2px 0 8px;padding-inline-start:12px;list-style:none}.teacher-toc__steps a{font-size:var(--fs-xs);line-height:var(--lh-ui);color:var(--muted);padding:6px 0;display:block}.teacher-toc__steps a:hover{color:var(--brand)}.teacher-main>section{padding-bottom:48px;scroll-margin-top:16px}.teacher .article-intro{max-width:none}.teacher-open{margin:0 0 8px}.teacher-main :is(.teacher-step,.teacher-card)[tabindex="-1"]:focus{outline:3px solid var(--brand);outline-offset:5px}.teacher :is(.teacher-summary,.teacher-html,.teacher-note,.teacher-choices,.teacher-setup,.teacher-goals){max-width:72ch}.teacher-lesson__steps{border-bottom:1.5px solid var(--line);margin:0 0 4px}.teacher-more.teacher-lesson__steps{border-top:0}.teacher-lesson__steps[open]{padding-bottom:18px}.teacher-lesson:has(+.teacher-catalogue) .teacher-lesson__steps{border-bottom:0}.teacher-float{bottom:max(16px, calc(env(safe-area-inset-bottom) + 8px));z-index:2;width:fit-content;margin:24px 0 0;margin-inline-start:auto;display:flex;position:sticky}.teacher-float:is(.is-away,.is-down):not(:focus-visible,:focus-within){opacity:0;pointer-events:none}@media (prefers-reduced-motion:no-preference){.teacher-float{transition:opacity .15s}}.teacher-main .section-heading{flex-wrap:wrap;justify-content:space-between;align-items:end;gap:12px 24px;display:flex}.teacher-main .section-heading>p{max-width:none}.teacher-lesson .section-heading h2{font-size:var(--fs-2xl)}.teacher-catalogue{border-top:1.5px solid var(--line-strong);padding-top:32px}.teacher-catalogue .teacher-html{color:var(--muted)}.teacher-card__more>summary{cursor:pointer;justify-content:space-between;align-items:center;gap:12px;min-height:44px;margin:-6px 0;list-style:none;display:flex}.teacher-card__more>summary::-webkit-details-marker{display:none}.teacher-card__more>summary:after{content:"";border:solid var(--brand);border-width:0 2px 2px 0;flex:none;width:7px;height:7px;transform:translateY(-2px)rotate(45deg)}.teacher-card__more[open]>summary:after{transform:translateY(2px)rotate(-135deg)}.teacher-card__more>summary:hover h3{color:var(--brand)}.teacher-catalogue .teacher-card h3{margin:0}.teacher-card__more[open]>summary{border-bottom:1.5px solid var(--line);margin-bottom:10px;padding-bottom:10px}@media (width>=1051px){.teacher-toc>ol{grid-template-columns:minmax(0,1fr);gap:2px}.teacher-toc.is-live li:not([data-current])>.teacher-toc__steps,.teacher-float{display:none}}.teacher h4{font-size:var(--fs-md);letter-spacing:var(--track-title);color:var(--ink);margin:20px 0 6px;font-weight:800}.teacher code{font-family:var(--mono);font-size:var(--fs-xs);overflow-wrap:break-word}.teacher :is(h2,h3,h4) code{font-size:inherit}.teacher-summary{max-width:720px;font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--muted);margin:0 0 20px}.teacher-note{font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--muted);margin:8px 0 0}.teacher-card{border:1.5px solid var(--line-strong);border-radius:var(--radius-lg);box-shadow:0 2px 0 var(--line-strong);background:#fff;padding:18px 20px}.teacher-card h3{font-size:var(--fs-md);letter-spacing:var(--track-title);margin:0 0 10px;font-weight:800}.teacher-empty{color:var(--muted);font-style:italic}.teacher-refs{gap:4px;margin:0;padding:0;list-style:none;display:grid}.teacher-refs a{margin-block:-10px;padding-block:12px;display:inline-block}.teacher-setup{font-size:var(--fs-sm);line-height:var(--lh-body);grid-template-columns:fit-content(200px) minmax(0,1fr);gap:6px 16px;margin:0;display:grid}.teacher-setup>div{grid-column:1/-1;grid-template-columns:subgrid;row-gap:2px;display:grid}@media (width<=599px){.teacher-setup{grid-template-columns:minmax(0,1fr)}}.teacher-setup dt{color:var(--muted);font-weight:600}.teacher-setup dd{color:var(--ink);margin:0}.teacher-setup dd>:first-child{margin-top:0}.teacher-setup dd p:last-child{margin-bottom:0}.teacher-flag{font-size:var(--fs-2xs);letter-spacing:var(--track-label);color:var(--brand-dark);border:1px solid var(--brand);border-radius:var(--radius-sm);vertical-align:1px;margin-inline-start:8px;padding:2px 6px;font-weight:700;display:inline-block}.teacher-flag--quiet{color:var(--muted);border-color:var(--control-edge);font-weight:500}.teacher-answer .teacher-flag{vertical-align:4px}.teacher-steps{gap:18px;margin:0;padding:0;list-style:none;display:grid}.teacher-step{border:1.5px solid var(--line-strong);border-radius:var(--radius-lg);box-shadow:0 2px 0 var(--line-strong);background:#fff;padding:22px 23px;scroll-margin-top:16px}.teacher-step__head{grid-template-columns:minmax(0,1fr) auto;align-items:center;gap:6px 16px;display:grid}.teacher-step__head .article-kicker{margin:0}.teacher-step__head h3{grid-column:1/-1}.teacher-step h3{font-size:var(--fs-xl);line-height:var(--lh-heading);letter-spacing:var(--track-title);margin:0;font-weight:800}.teacher-item{border-top:1.5px solid var(--line);margin-top:20px;padding-top:16px}.teacher-item__kind{margin:0}.teacher-more{border-top:1.5px solid var(--line);margin-top:18px}.teacher-choices+.teacher-more{border-top:0}.teacher-more>summary{min-height:44px;font-size:var(--fs-sm);color:var(--brand);cursor:pointer;align-items:center;gap:10px;padding-top:6px;font-weight:700;list-style:none;display:flex}.teacher-more>summary::-webkit-details-marker{display:none}.teacher-more>summary:after{content:"";border:solid var(--brand);border-width:0 2px 2px 0;flex:none;width:7px;height:7px;transform:translateY(-2px)rotate(45deg)}.teacher-more[open]>summary:after{transform:translateY(2px)rotate(-135deg)}.teacher-more>h4:first-of-type{margin-top:8px}.teacher-setup--after{margin-top:12px}.teacher-path{font-size:var(--fs-xs);line-height:var(--lh-ui);color:var(--muted);overflow-wrap:anywhere;display:block}.teacher-path code{font-size:inherit}.teacher-html{font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--ink)}.teacher-html p{margin:0 0 8px}.teacher-html>:last-child{margin-bottom:0}.teacher-html .math-display{display:block;overflow-x:auto}.teacher-answer{font-family:var(--mono);font-size:var(--fs-xl);color:var(--brand-dark);margin:0;font-weight:700}.teacher-goals{gap:10px;margin:0;padding:0;list-style:none;display:grid}.teacher-choices{gap:8px;margin:0;padding:0;list-style:none;display:grid}.teacher-choices>li{border:1.5px solid var(--line);border-radius:var(--radius);font-size:var(--fs-sm);line-height:var(--lh-body);padding:10px 12px}.teacher-choices>li.is-correct{border-color:var(--brand);background:var(--tint)}.teacher-choice__head{margin:0}.teacher-verdict{min-width:52px;font-size:var(--fs-sm);letter-spacing:var(--track-label);color:var(--muted);margin-inline-end:8px;font-weight:800;display:inline-block}.teacher-verdict.is-correct{color:var(--brand-dark)}.teacher-verdict.is-correct:before{content:"✓ "}.teacher-misc{font-size:var(--fs-sm);line-height:var(--lh-body);color:var(--muted);margin:6px 0 0}.teacher-misc strong{color:var(--ink)}.teacher-feedback{border-radius:var(--radius);background:var(--paper);border:1px solid var(--line);margin-top:8px;padding:10px 12px}.teacher-choices .teacher-feedback{border-radius:var(--radius-sm)}.teacher-feedback.is-correct{background:var(--tint);border-color:var(--brand);margin-top:18px}.teacher-feedback__label{font-size:var(--fs-sm);letter-spacing:var(--track-label);color:var(--muted);margin:0 0 4px;font-weight:800}.teacher-misconceptions{border-top:1.5px solid var(--line);margin:0;padding:0;list-style:none;display:grid}.teacher-misconceptions>.teacher-card{border:0;border-bottom:1.5px solid var(--line);box-shadow:none;background:0 0;border-radius:0;padding:8px 0}.teacher-misconceptions>li{font-size:var(--fs-sm);scroll-margin-top:16px}@media (width<=767px){.learn-group-nav{display:none}.learn-group+.learn-group{margin-top:40px}.learn-group__head h3{font-size:var(--fs-xl)}#units-title{font-size:var(--fs-2xl)}.learn-cards:has(>li[data-unit]){border-bottom:1.5px solid var(--line-strong);display:block}.learn-cards>li[data-unit]{border:0;border-top:1.5px solid var(--line-strong);box-shadow:none;background:0 0;border-radius:0;padding:12px 0 13px;display:block}.learn-group .learn-cards>li[data-unit]:first-child{border-top:0;padding-top:0}.learn-group .learn-cards:has(>li[data-unit]){border-bottom:0}.learn-group__head p{flex-basis:100%}.learn-cards>li[data-unit]:is(:hover,:active){box-shadow:none;transform:none}.learn-cards>li[data-unit]:has(:is(h3,h4) a:focus-visible){outline-offset:2px}li[data-unit]>.article-kicker{margin:0 0 4px}li[data-unit] .learn-card__title{font-size:var(--fs-lg);line-height:var(--lh-ui);margin:0}li[data-unit]>.learn-card__summary{display:none}.progress-totals{gap:0 10px}.progress-backup{grid-template-columns:minmax(0,1fr)}.progress-backup>*,.progress-backup>.progress-backup__head{grid-area:auto/1}.progress-totals li{padding:10px 12px 12px}.progress-totals__bar{margin-top:10px}.progress-totals__label{font-size:var(--fs-xs)}.progress-totals__figure{font-size:var(--fs-xl)}.progress-unit__head,.progress-lesson__head,.progress-items li{grid-template-columns:minmax(0,1fr)}.progress-items li{padding-bottom:8px}.progress-items a{padding-bottom:2px}.learn-shell>section{padding-bottom:40px}.learn-next{margin-bottom:40px}.learn-units{padding-top:16px}.learn-shell>.learn-cards{margin-bottom:40px}.learn-lesson{grid-template-columns:auto minmax(0,1fr) auto;gap:6px 10px}.learn-lesson__number{grid-area:1/1;padding:0;position:static}.learn-lesson>div{grid-column:2;padding:0}.learn-lesson__go{grid-column:3}.learn-lesson p.learn-lesson__meta{text-align:start;grid-area:2/2;justify-content:flex-start;gap:4px 12px}.hero-actions--trio{grid-template-columns:repeat(2,minmax(0,1fr));display:grid}.hero-actions--trio>:first-child{grid-column:1/-1}.hero-actions--trio>.article-button{justify-content:center}.lesson-hero .article-intro>p{margin-bottom:0}.lesson-steps{display:none}.lesson-steps-index{margin-top:4px}.lesson-jump{display:block}.lesson-texts{padding-top:26px}.practice{padding:18px}.practice__head{margin-bottom:14px}.lesson-pager{grid-template-columns:repeat(2,minmax(0,1fr));grid-template-areas:"back next"".note"}.lesson-pager .article-button{justify-content:center}.lesson-pager__long{display:none}.lesson-pager__short{display:inline}.teacher-toc{display:none}.teacher-step{padding:16px 14px}.teacher-step h3{font-size:var(--fs-lg)}.teacher-lesson .section-heading h2{font-size:var(--fs-xl)}.teacher-lesson>.teacher-summary{margin-bottom:14px}.teacher-choices>li,.teacher-feedback{padding:8px 10px}.teacher-setup{gap:10px}.teacher-setup>div{grid-template-columns:minmax(0,1fr);gap:0}.teacher-misconceptions>.teacher-card{padding-block:12px}.teacher-card__more>summary{margin:0}.teacher-card__more>summary h3{line-height:var(--lh-ui)}.teacher-main>.teacher-catalogue{padding-bottom:0}.teacher-float{margin-top:26px}}@media (pointer:coarse){.lesson-steps a{padding-block:12px}.teacher-toc__lesson{padding-block:11.5px}.teacher-toc__steps a{padding-block:13px}}@media (forced-colors:active){.progress-totals__bar{forced-color-adjust:none;background:linear-gradient(to right, Highlight var(--done,0%), GrayText var(--done,0%))}[dir=rtl] .progress-totals__bar{background:linear-gradient(to left, Highlight var(--done,0%), GrayText var(--done,0%))}.progress-meter__dots span{forced-color-adjust:none;background:canvas;border-color:canvastext}.progress-meter__dots span[data-state=done]{background:highlight;border-color:highlight}.progress-meter__dots span[data-state=tried]{background:linear-gradient(90deg,highlight 50%,canvas 50%);border-color:highlight}[dir=rtl] .progress-meter__dots span[data-state=tried]{background:linear-gradient(270deg,highlight 50%,canvas 50%)}.lesson-mark[data-state=started]:before{forced-color-adjust:none;background:linear-gradient(90deg,highlight 50%,canvas 50%);border-color:highlight}[dir=rtl] .lesson-mark[data-state=started]:before{background:linear-gradient(-90deg,highlight 50%,canvas 50%)}}@media (width<=479px){.progress-totals{grid-template-rows:none;grid-template-columns:minmax(0,1fr);gap:10px}.progress-totals li{grid-row:auto;grid-template-rows:auto auto;grid-template-columns:auto minmax(0,1fr);align-items:baseline;column-gap:12px}.progress-totals__figure{grid-area:1/1}.progress-totals__label{font-size:var(--fs-sm);grid-area:1/2}.progress-totals__bar{grid-area:2/1/auto/-1}}