:root{color-scheme:light;--space-3xs: 2px;--space-2xs: 4px;--space-xs: 8px;--space-sm: 12px;--space-md: 16px;--space-lg: 24px;--space-xl: 40px;--space-2xl: 64px;--space-3xl: 96px;--space-4xl: 144px;--text-xs: .75rem;--text-sm: .875rem;--text-md: 1rem;--text-lg: 1.2rem;--text-xl: 1.44rem;--text-2xl: 1.728rem;--text-3xl: 2.074rem;--text-display-s: 1.44rem;--text-display: 1.728rem;--text-section: 1.2rem;--text-title: 1rem;--text-lead: 1rem;--ease-out: cubic-bezier(.16, 1, .3, 1);--ease-in: cubic-bezier(.7, 0, .84, 0);--ease-in-out: cubic-bezier(.65, 0, .35, 1);--dur-micro: .12s;--dur-short: .22s;--dur-long: .42s;--color-error: oklch(52% .19 27);--color-success: oklch(50% .12 150);--container: 1440px;--gutter: 64px;--gap-columns: 32px;--section-gap-s: 120px;--section-gap: 144px;--section-gap-l: 176px;--z-base: 1;--z-raised: 10;--z-dropdown: 100;--z-sticky: 200;--z-sticky-nav: 300;--z-modal: 400;--z-toast: 500;--z-tooltip: 600;--color-paper: oklch(96% .011 85);--color-paper-2: oklch(99.5% .005 85);--color-paper-3: oklch(92% .016 85);--color-ink: oklch(18% .006 60);--color-ink-2: oklch(28% .008 60);--color-muted: oklch(44% .012 60);--color-rule: oklch(88% .013 85);--color-accent: oklch(70% .19 40);--color-accent-ink: oklch(18% .006 60);--color-accent-soft: oklch(91% .05 50);--color-focus: oklch(60% .19 40);--color-green: oklch(48% .11 150);--color-green-soft: oklch(92% .04 150);--color-contour: oklch(62% .07 58);--color-water: oklch(60% .05 232);--color-hedge: oklch(50% .1 150);--color-grid: oklch(90% .014 85);--color-grid-strong: oklch(85% .018 85);--color-sheet: oklch(99.3% .004 85);--font-display: "Red Hat Display", "Red Hat Text", ui-sans-serif, sans-serif;--font-body: "Red Hat Text", ui-sans-serif, system-ui, sans-serif;--font-outlier: "Red Hat Mono", ui-monospace, monospace;--radius-card: 10px;--radius-entry: 14px;--radius-pill: 6px;--rule-hair: 1px;--shadow-card: 0 1px 2px oklch(18% .006 60 / .08), 0 14px 28px -16px oklch(18% .006 60 / .28);--shadow-lift: 0 1px 1px oklch(18% .006 60 / .1), 0 2px 4px -1px oklch(18% .006 60 / .1), 0 24px 44px -20px oklch(18% .006 60 / .42);--tracking-display: -.035em;--display-weight: 600}:root{--font-body: ui-sans-serif, system-ui, -apple-system, sans-serif;--font-display: var(--font-body);--color-error: #9e2922;--color-transparent: transparent;--space-page: 48px}*{box-sizing:border-box}html{overflow-x:clip}body{overflow-x:clip;margin:0;background:var(--color-paper);color:var(--color-ink);font-family:var(--font-body);font-size:16px;line-height:1.6}button,input,textarea{font:inherit}a{color:var(--color-ink);text-underline-offset:4px}button,.button{display:inline-flex;align-items:center;justify-content:center;min-height:44px;padding:var(--space-xs) var(--space-md);border:1px solid var(--color-rule);border-radius:6px;color:var(--color-ink);background:var(--color-paper-2);font-weight:500;cursor:pointer;text-decoration:none}button:hover,.button:hover{background:var(--color-paper-3)}button:active{transform:translateY(1px)}button:disabled{opacity:.55;cursor:not-allowed;transform:none}button[aria-busy=true]{cursor:progress}.primary{background:var(--color-accent);border-color:var(--color-accent);color:var(--color-accent-ink)}.primary:hover{background:var(--color-accent-soft)}.quiet,.plain{background:var(--color-transparent);border-color:var(--color-transparent)}:focus-visible{outline:3px solid var(--color-focus);outline-offset:3px}input,textarea{width:100%;min-width:0;padding:var(--space-sm) var(--space-md);border:1px solid var(--color-muted);border-radius:6px;background:var(--color-paper-2);color:var(--color-ink)}input{min-height:44px}input:disabled{background:var(--color-paper-3)}textarea{resize:vertical}label{display:block;font-size:.875rem;margin-bottom:var(--space-xs)}form{display:grid;gap:var(--space-sm)}form>button{justify-self:start;margin-top:var(--space-sm)}h1,h2,h3{font-family:var(--font-display);font-weight:600;line-height:1.22;min-width:0;overflow-wrap:break-word;color:var(--color-ink)}h1{font-size:2rem;margin:0 0 var(--space-md);letter-spacing:-.035em}h2{font-size:1.5rem;margin:0 0 var(--space-md)}h3{font-size:1.125rem}p{margin:0 0 var(--space-md)}hr{border:0;border-top:1px solid var(--color-rule);margin:var(--space-xl) 0}.shell{width:calc(100% - 64px);max-width:1280px;margin-inline:auto}.topbar{border-bottom:1px solid var(--color-rule)}.bar{display:flex;align-items:center;min-height:56px;gap:var(--space-lg)}.wordmark{font-size:1.25rem;font-weight:650;padding:0;letter-spacing:-.06em}.wordmark>span:first-child{font-weight:400}.brand-mark{color:var(--color-muted);margin-left:var(--space-md);font-weight:400}nav{display:flex;gap:var(--space-xs)}nav button{font-size:var(--text-sm);background:var(--color-transparent);border-color:var(--color-transparent);color:var(--color-muted)}nav button[aria-current=page]{color:var(--color-ink);background:var(--color-paper-3)}.account{font-size:var(--text-sm);margin-left:auto}.page{padding-block:var(--space-page);min-height:65vh}.narrow{max-width:760px;margin-inline:auto}.page-heading{display:flex;align-items:center;justify-content:space-between;gap:var(--space-lg);margin-bottom:var(--space-xl)}.page-heading h1{margin-bottom:var(--space-xs)}.muted,.small{color:var(--color-muted)}.small{font-size:.875rem}.error{border:1px solid var(--color-error);padding:var(--space-md);color:var(--color-error);margin-block:var(--space-md);background:var(--color-paper-2)}.actions{display:flex;flex-wrap:wrap;gap:var(--space-sm);align-items:center}.signin{display:grid;grid-template-columns:minmax(0,1.15fr) minmax(0,1fr);gap:var(--space-3xl);align-items:center;min-height:72vh;padding-block:var(--space-2xl)}.signin-intro{max-width:540px}.signin-intro h1{font-size:3.2rem;margin-bottom:var(--space-lg)}.signin-intro p{max-width:420px;font-size:1.125rem}.book-line{display:block;width:48px;height:6px;background:var(--color-accent);margin-bottom:var(--space-xl)}.signin-form{max-width:440px;padding:var(--space-xl);background:var(--color-paper-2);border:1px solid var(--color-rule);border-radius:10px}.signin-form>.small{margin-top:var(--space-xl);margin-bottom:0}.signin-form form{margin-top:var(--space-lg)}.signin-form form button{width:100%}.footer{display:flex;justify-content:space-between;border-top:1px solid var(--color-rule);padding-block:var(--space-lg);font-size:.875rem;color:var(--color-muted);gap:var(--space-md)}.library-toolbar{display:flex;justify-content:space-between;align-items:end;gap:var(--space-lg);padding-bottom:var(--space-lg);border-bottom:1px solid var(--color-ink)}.search{width:280px;font-size:.875rem}.search input{margin-top:var(--space-xs)}.course-feature{display:grid;grid-template-columns:minmax(0,.8fr) minmax(0,1.8fr);gap:var(--space-2xl);padding-block:var(--space-xl);align-items:center;border-bottom:1px solid var(--color-rule)}.course-spine{display:flex;flex-direction:column;justify-content:center;background:var(--color-ink-2);color:var(--color-paper);padding:var(--space-xl);border-left:8px solid var(--color-accent);min-height:280px;font-size:2.1rem;line-height:1.15;letter-spacing:-.03em}.spine-author{font-size:.875rem;line-height:1.6;margin-top:var(--space-xl);letter-spacing:normal}.course-summary{max-width:650px}.course-summary h2{font-size:1.75rem}.progress-label{display:flex;justify-content:space-between;font-size:.875rem;color:var(--color-muted);margin-top:var(--space-xl)}progress{width:100%;height:6px;accent-color:var(--color-green);margin-bottom:var(--space-lg)}.empty{padding:var(--space-2xl) 0;max-width:650px}.empty form{max-width:400px;margin-top:var(--space-xl)}details{border-bottom:1px solid var(--color-rule);padding-block:var(--space-md)}summary{cursor:pointer;min-height:44px;padding-block:var(--space-sm);font-weight:500}details form{padding-block:var(--space-md)}.collection-settings{max-width:440px;margin-top:var(--space-lg);border:0}.lesson-list{list-style:none;padding:0;border-top:1px solid var(--color-ink);margin-top:var(--space-xl)}.lesson-list li{border-bottom:1px solid var(--color-rule)}.lesson-list button{display:grid;grid-template-columns:44px minmax(0,1fr) auto;width:100%;text-align:left;gap:var(--space-lg);min-height:80px;border:0;border-radius:0;background:var(--color-transparent)}.lesson-list button:hover{background:var(--color-paper-3)}.lesson-number{color:var(--color-muted);font-variant-numeric:tabular-nums}.lesson-status{color:var(--color-muted);font-size:.875rem}.lesson-page{padding-top:var(--space-md)}.lesson-page h1{font-size:1.25rem;margin:0}.lesson-page .page-heading{flex-direction:row;align-items:center;gap:var(--space-sm);margin-bottom:var(--space-sm)}.lesson-page .page-heading>button{flex-shrink:0;font-size:var(--text-sm)}.lesson-page>.quiet{margin:0;min-height:32px;padding:0;font-size:var(--text-sm)}.workspace{display:grid;grid-template-columns:minmax(0,1fr);gap:var(--space-xl)}.workspace.with-tools{grid-template-columns:minmax(0,2fr) minmax(300px,1fr)}.video-area{max-width:960px;margin-inline:auto;position:relative;background:var(--color-ink);color:var(--color-paper);aspect-ratio:16 / 9}.video,.video iframe{width:100%;height:100%;border:0}.player-message{position:absolute;inset:20% 10%;padding:var(--space-lg);background:var(--color-ink);color:var(--color-paper)}.resource-row{display:flex;flex-wrap:wrap;gap:var(--space-md);padding-block:var(--space-md);font-size:.875rem}.resource-row>span{margin-left:auto}.resume{background:var(--color-paper-3);padding:var(--space-2xl);min-height:300px;display:flex;flex-direction:column;justify-content:center}.lesson-controls{display:flex;justify-content:space-between;gap:var(--space-sm);flex-wrap:wrap;padding-top:var(--space-xl)}.study-tools{border-left:1px solid var(--color-rule);padding-left:var(--space-lg)}.study-tools h2{font-size:1.25rem}.notes{padding:0;list-style:none}.notes li{padding-block:var(--space-md);border-bottom:1px solid var(--color-rule)}.notes p,.answer p{white-space:pre-wrap;overflow-wrap:anywhere}.timestamp{font-size:.875rem;color:var(--color-ink);background:var(--color-accent-soft);padding:var(--space-xs) var(--space-sm);margin-bottom:var(--space-sm)}.checkbox{display:flex;align-items:center;gap:var(--space-sm);margin-block:var(--space-md)}.checkbox input{width:20px;height:20px;min-height:20px;flex-shrink:0;accent-color:var(--color-ink)}.review-question{padding-block:var(--space-xl);border-top:1px solid var(--color-ink)}.review-question h2{font-size:1.75rem;margin-bottom:var(--space-xl)}.answer{padding-block:var(--space-lg);border-top:1px solid var(--color-rule);margin-top:var(--space-xl)}.ratings{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:var(--space-sm);margin-bottom:var(--space-lg)}.ratings button{flex-direction:column;padding:var(--space-md) var(--space-xs)}.ratings small{font-size:.75rem;font-weight:400}.suspended{padding-block:var(--space-md)}.loading{padding-block:var(--space-2xl)}.skip{position:absolute;transform:translateY(-200%);background:var(--color-ink);color:var(--color-paper);padding:var(--space-sm) var(--space-md);z-index:10}.skip:focus-visible{transform:translateY(0)}@media(max-width:800px){.shell{width:calc(100% - 32px)}.bar{min-height:56px;gap:var(--space-xs);flex-wrap:wrap;padding-block:0}.brand-mark{display:none}nav button{padding-inline:var(--space-sm)}.wordmark{font-size:1.25rem}.signin{grid-template-columns:minmax(0,1fr);gap:var(--space-xl)}.signin-intro h1{font-size:2.5rem}.signin-form{max-width:none}.course-feature{grid-template-columns:minmax(0,1fr);gap:var(--space-lg)}.course-spine{min-height:220px}.workspace.with-tools{grid-template-columns:minmax(0,1fr)}.study-tools{border-left:0;border-top:1px solid var(--color-rule);padding:var(--space-lg) 0}.page-heading{align-items:start;flex-direction:column;gap:var(--space-md)}.lesson-list button{grid-template-columns:30px minmax(0,1fr);gap:var(--space-sm)}.lesson-status{grid-column:2}.library-toolbar{align-items:start;flex-direction:column}.search{width:100%}.ratings{grid-template-columns:repeat(2,minmax(0,1fr))}.footer{flex-direction:column}.page{padding-block:var(--space-xl)}.lesson-page{padding-top:var(--space-sm)}}@media(prefers-reduced-motion:reduce){*,*:before,*:after{scroll-behavior:auto!important;animation:none!important;transition:none!important}}h1,h2{text-wrap:balance}::selection{background:var(--color-accent-soft);color:var(--color-ink)}:root{scrollbar-color:var(--color-muted) var(--color-paper);caret-color:var(--color-ink)}.player-error{border:1px solid var(--color-rule);padding:var(--space-md);margin-top:var(--space-md);background:var(--color-paper-2)}.transcript-segments{max-height:440px;overflow-y:auto;padding:var(--space-sm);list-style:none}.transcript-segments li{display:flex;align-items:start;gap:var(--space-md);padding-block:var(--space-xs)}.transcript-segments button{flex-shrink:0}.transcript-toolbar{display:grid;grid-template-columns:minmax(0,11rem) minmax(0,1fr) auto;grid-template-areas:"language search follow";gap:var(--space-xs);margin-block:var(--space-md)}.transcript-toolbar select,.transcript-toolbar input{width:100%;min-width:0;min-height:44px;margin:0;padding:var(--space-xs) var(--space-sm);border:1px solid var(--color-rule);border-radius:4px;background:var(--color-paper-2);color:var(--color-ink);font:inherit}.transcript-segments span{min-width:0}.transcript-about{border:0;padding-block:var(--space-xs);font-size:var(--text-sm)}.transcript-about summary{color:var(--color-muted);font-weight:400;font-size:inherit}@media(max-width:480px){.transcript-toolbar{grid-template-columns:minmax(0,1fr) auto;grid-template-areas:"language follow" "search search"}}.transcript-toolbar select{grid-area:language}.transcript-toolbar input{grid-area:search}.transcript-follow{grid-area:follow;white-space:nowrap}.transcript-follow[aria-pressed=true]{background:var(--color-accent-soft)}.transcript-segments li{border-left:3px solid transparent;padding-inline:var(--space-xs)}.transcript-segments li[aria-current=time]{border-left-color:var(--color-accent);background:var(--color-accent-soft);border-radius:4px}.transcript-segments mark{background:#ffd59e;color:var(--color-ink);padding-block:2px;box-decoration-break:clone;-webkit-box-decoration-break:clone}.transcript-segments li[aria-current=time] .timestamp{background:var(--color-accent);border-color:var(--color-accent);color:var(--color-accent-ink)}