.lpc-flip{transform:scaleX(-1)}.lpc-rail-title{font-size:16px;font-weight:700;line-height:1.3;letter-spacing:-.01em;color:var(--text)}.lpc-rail-track{width:100%;height:6px;overflow:hidden;border-radius:9999px;background:color-mix(in srgb,var(--text) 10%,transparent)}.lpc-rail-lesson{overflow:hidden;border-radius:.75rem}.lpc-rail-caret{color:var(--text-muted);transform:rotate(90deg);transition:transform .26s ease}.lesson-rail-topic[data-expanded=true] .lpc-rail-caret{transform:rotate(-90deg)}.lpc-rail-kind{color:var(--text-muted)}.lpc-rail-done{color:color-mix(in srgb,var(--subject-tint) 70%,var(--text))}.lpc-rail-live{flex-shrink:0;color:var(--text)}.lpc-rail-spine-rule{width:1px;height:10px;background:color-mix(in srgb,var(--text) 10%,transparent)}.lpc-topic-progress{position:relative;width:100%;height:2px;overflow:hidden;background:color-mix(in srgb,var(--palette-white) 5%,transparent)}.lpc-video-fs{position:absolute;top:.5rem;right:.5rem;display:none;align-items:center;justify-content:center;width:2rem;height:2rem;border-radius:9999px;border:1px solid color-mix(in srgb,var(--palette-white) 20%,transparent);background:color-mix(in srgb,var(--palette-black) 50%,transparent);color:var(--palette-white);backdrop-filter:blur(12px);-webkit-backdrop-filter:blur(12px);transition:background-color .15s ease}.lpc-video-fs:hover{background:color-mix(in srgb,var(--palette-black) 70%,transparent)}.lpc-video-fs:focus-visible{outline:2px solid var(--brand);outline-offset:2px}@media (min-width:1024px){.lpc-video-fs{display:flex}}@media (prefers-reduced-motion:reduce){.lpc-rail-caret,.lpc-video-fs{transition:none}}html[data-skin=sketchbook]{--lpc-ink:var(--skin-ink);--lpc-round:47% 53% 50% 50%/53% 47% 53% 47%}html.dark[data-skin=sketchbook]{--lpc-ink:var(--skin-ink-strong)}html[data-skin=sketchbook] .lesson-presentation-root{--lpc-hatch:repeating-linear-gradient(45deg,var(--lesson-solid) 0 2px,color-mix(in srgb,var(--subject-tint) 18%,var(--surface-solid)) 2px 6px)}html[data-skin=sketchbook] .lesson-rail,html[data-skin=sketchbook] .lesson-rail-spine{background:var(--surface);border-right:var(--skin-line) solid var(--lpc-ink);backdrop-filter:none;-webkit-backdrop-filter:none}html[data-skin=sketchbook] .lesson-rail.is-drawer{box-shadow:4px 0 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] .lesson-rail-scrim{backdrop-filter:none;-webkit-backdrop-filter:none}html[data-skin=sketchbook] :is(.lesson-rail-head,.lesson-rail-progress){border-bottom:var(--skin-line) dashed var(--skin-divider)}html[data-skin=sketchbook] .lesson-rail-foot{border-top:var(--skin-line) dashed var(--skin-divider)}html[data-skin=sketchbook] .lesson-rail-pulse{background:var(--lesson-solid)}html[data-skin=sketchbook] .lpc-rail-track{height:10px;background:var(--surface-solid);border:var(--skin-line) solid var(--lpc-ink);border-radius:var(--skin-wobble-sm)}html[data-skin=sketchbook] .lesson-rail-progress-fill{background:var(--lpc-hatch);border-right:var(--skin-line) solid var(--lpc-ink);border-radius:0}html[data-skin=sketchbook] .lesson-rail-progress-fill[style*="width: 0%"]{border-right:0}html[data-skin=sketchbook] .lpc-rail-lesson{position:relative;border:var(--skin-line) solid transparent;border-radius:var(--skin-wobble-sm)}@media (min-width:1024px){html[data-skin=sketchbook] .lesson-rail:not(.is-drawer) .lpc-rail-lesson[data-current-lesson=false][data-expanded=false]:after{content:"";position:absolute;right:8px;bottom:0;left:8px;height:1px;background:color-mix(in srgb,var(--skin-wavy) 55%,transparent);pointer-events:none}}html[data-skin=sketchbook] .lpc-rail-lesson[data-current-lesson=true]{background:var(--skin-wash-mist);border-color:var(--lpc-ink)}html[data-skin=sketchbook] .lpc-rail-lesson[data-current-lesson=true][data-expanded=true]{background:var(--surface-solid)}html[data-skin=sketchbook] .lpc-rail-lesson[data-current-lesson=false][data-expanded=true]{background:var(--surface);border-style:dashed;border-color:var(--skin-future)}html[data-skin=sketchbook] .lesson-rail-topic{border-radius:0}html[data-skin=sketchbook] .lesson-rail-topic:hover,html[data-skin=sketchbook] .lesson-rail-topic[data-expanded=true]:hover{background:var(--skin-wash-butter)}html[data-skin=sketchbook] .lesson-rail-topic[data-expanded=true],html[data-skin=sketchbook] .lesson-rail-topic[data-expanded=true][data-state=active]{background:transparent;border-bottom:var(--skin-line) dashed var(--skin-divider)}html[data-skin=sketchbook] .lesson-rail-dot{background:transparent;border:var(--skin-line) dashed var(--skin-future);border-radius:var(--skin-wobble-sm);color:var(--text-muted)}html[data-skin=sketchbook] .lesson-rail-dot[data-state=done]{background:var(--skin-wash-sage);border-style:solid;border-color:var(--lpc-ink);color:var(--ok)}html[data-skin=sketchbook] .lesson-rail-dot[data-state=active]{background:var(--lesson-solid);border-style:solid;border-color:var(--lpc-ink);color:var(--lesson-on-solid)}html[data-skin=sketchbook] .lesson-rail-dot.is-spine:hover{background:var(--skin-wash-butter)}html[data-skin=sketchbook] .lesson-rail-dot.is-spine[data-state=active]:hover{background:var(--lesson-solid)}html[data-skin=sketchbook] .lesson-rail-slide{border:var(--skin-line) solid transparent;border-radius:var(--skin-wobble-sm)}html[data-skin=sketchbook] .lesson-rail-slide:hover{background:var(--skin-wash-butter)}html[data-skin=sketchbook] .lesson-rail-slide[data-state=partial],html[data-skin=sketchbook] .lesson-rail-slide[data-state=skipped],html[data-skin=sketchbook] .lesson-rail-slide[data-state=watched]{border-color:transparent}html[data-skin=sketchbook] .lesson-rail-slide[data-current=true]{background:var(--skin-wash-mist);border-style:solid;border-color:var(--lpc-ink);box-shadow:2px 2px 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] .lesson-rail-slide[data-current=true] .lpc-rail-kind{color:var(--text)}html[data-skin=sketchbook] .lesson-rail-skip-ring{border-color:var(--skin-future)}html[data-skin=sketchbook] .lesson-rail-tick{height:6px;background:transparent;border-radius:2px;box-shadow:inset 0 0 0 1px var(--skin-future)}html[data-skin=sketchbook] .lesson-rail-tick[data-state=watched]{background:var(--lpc-hatch);box-shadow:inset 0 0 0 1px var(--lpc-ink)}html[data-skin=sketchbook] .lesson-rail-tick[data-state=partial]{background:var(--skin-wash-mist);box-shadow:inset 0 0 0 1px var(--lpc-ink)}html[data-skin=sketchbook] .lesson-rail-tick[data-state=skipped]{box-shadow:none;outline:1px dashed var(--skin-future);outline-offset:-1px}html[data-skin=sketchbook] .lesson-rail-tick[data-state=active]{background:var(--lesson-solid);box-shadow:inset 0 0 0 1px var(--lpc-ink)}html[data-skin=sketchbook] :is(.lesson-rail-open,.lesson-rail-quiz){background:var(--surface-solid);border:var(--skin-line) solid var(--lpc-ink);border-radius:var(--skin-wobble-btn);box-shadow:2px 3px 0 var(--skin-shadow-ink);transition:translate .12s ease,box-shadow .12s ease,background-color .12s ease}html[data-skin=sketchbook] .lesson-rail-quiz{font-size:13px}html[data-skin=sketchbook] :is(.lesson-rail-open,.lesson-rail-quiz):hover{background:var(--skin-wash-butter);translate:-1px -1px;box-shadow:3px 4px 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] :is(.lesson-rail-open,.lesson-rail-quiz):active{translate:1px 1px;box-shadow:0 0 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] .lesson-rail-iconbtn{background:var(--surface-solid);border:var(--skin-line) solid var(--lpc-ink);border-radius:var(--skin-wobble-sm);color:var(--text)}html[data-skin=sketchbook] .lesson-panel-spine:hover .lesson-rail-iconbtn,html[data-skin=sketchbook] .lesson-rail-iconbtn:hover{background:var(--skin-wash-butter)}html[data-skin=sketchbook] .lesson-panel-spine:hover .lesson-rail-iconbtn.is-tinted,html[data-skin=sketchbook] .lesson-rail-iconbtn.is-tinted{background:var(--skin-wash-mist)}html[data-skin=sketchbook] .lesson-panel-spine,html[data-skin=sketchbook] .lesson-panel-spine:hover{background:transparent}html[data-skin=sketchbook] .lesson-nowplaying{background:var(--surface);backdrop-filter:none;-webkit-backdrop-filter:none;border-bottom-color:var(--lpc-ink)}html[data-skin=sketchbook] .lpc-topic-progress{height:3px;background:transparent}html[data-skin=sketchbook] .lesson-light-ray{background:var(--lesson-solid)}html[data-skin=sketchbook] .lesson-nowplaying-count{background:var(--skin-wash-mist);border-radius:var(--skin-wobble-sm);box-shadow:inset 0 0 0 1px color-mix(in srgb,var(--lpc-ink) 45%,transparent);color:var(--text)}html[data-skin=sketchbook] .lesson-nowplaying-nav{background:var(--surface-solid);border-color:var(--lpc-ink);border-radius:var(--skin-wobble-btn);box-shadow:inset 0 0 0 .5px var(--lpc-ink),2px 2px 0 var(--skin-shadow-ink);color:var(--text)}html[data-skin=sketchbook] .lesson-nowplaying-nav:hover{background:var(--skin-wash-butter)}html[data-skin=sketchbook] .is-phone .lesson-nowplaying-nav{box-shadow:inset 0 0 0 .5px var(--lpc-ink)}html[data-skin=sketchbook] .lesson-nowplaying-back{border-radius:var(--skin-wobble-sm)}html[data-skin=sketchbook] .lesson-nowplaying-back:hover{background:var(--skin-wash-butter)}html[data-skin=sketchbook] .lesson-glass-chip{position:relative;background:var(--surface-solid);border-color:var(--lpc-ink);border-radius:var(--skin-wobble-btn);box-shadow:inset 0 0 0 .5px var(--lpc-ink),2px 3px 0 var(--skin-shadow-ink);backdrop-filter:none;-webkit-backdrop-filter:none;color:var(--text)}@media (min-width:1024px){html[data-skin=sketchbook] .lesson-glass-chip:before{content:"";position:absolute;top:-5px;left:-11px;width:42px;height:15px;rotate:-34deg;background:color-mix(in srgb,color-mix(in srgb,var(--warn) 22%,var(--skin-wash-butter)) 80%,transparent);border-left:1px dashed color-mix(in srgb,var(--skin-ink) 35%,transparent);border-right:1px dashed color-mix(in srgb,var(--skin-ink) 35%,transparent);pointer-events:none}html.dark[data-skin=sketchbook] .lesson-glass-chip:before{background:color-mix(in srgb,var(--warn) 30%,transparent);border-color:color-mix(in srgb,var(--text) 25%,transparent)}}html[data-skin=sketchbook] .lesson-presentation-root:not(.is-phone) .lesson-stage:not(.is-fullscreen):not(:fullscreen) .lesson-video-frame{border-radius:var(--skin-wobble-a);box-shadow:0 0 0 var(--skin-line) var(--lpc-ink),3px 4px 0 var(--skin-line) var(--skin-shadow-ink)}html[data-skin=sketchbook] .lpc-video-fs{background:var(--surface-solid);border:var(--skin-line) solid var(--lpc-ink);border-radius:var(--lpc-round);box-shadow:2px 2px 0 var(--skin-shadow-ink);color:var(--text);backdrop-filter:none;-webkit-backdrop-filter:none}html[data-skin=sketchbook] .lpc-video-fs:hover{background:var(--skin-wash-butter)}html[data-skin=sketchbook] .lesson-caption-line{border-radius:var(--skin-wobble-sm)}html[data-skin=sketchbook] .lesson-notice-card{border-color:var(--lpc-ink);box-shadow:4px 5px 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] .lesson-notice-icon{color:var(--text)}html[data-skin=sketchbook] .lesson-notice-primary{border:var(--skin-line) solid var(--lpc-ink);border-radius:var(--skin-wobble-btn);box-shadow:2px 3px 0 var(--skin-shadow-ink);transition:translate .12s ease,box-shadow .12s ease}html[data-skin=sketchbook] .lesson-notice-primary:hover{translate:-1px -1px;box-shadow:3px 4px 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] .lesson-notice-primary:active{translate:1px 1px;box-shadow:0 0 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] .lesson-notice-secondary{border:var(--skin-line) dashed var(--skin-future);border-radius:var(--skin-wobble-btn)}html[data-skin=sketchbook] .lesson-notice-secondary:hover{background:var(--skin-wash-butter)}html[data-skin=sketchbook] .lesson-notice-chip{border:var(--skin-line) solid var(--lpc-ink);border-radius:var(--skin-wobble-sm);box-shadow:2px 2px 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] .lesson-notice-chip-btn{border-radius:var(--skin-wobble-sm)}html[data-skin=sketchbook] .lesson-landscape-btn{background:var(--surface-solid);border:var(--skin-line) solid var(--lpc-ink);border-radius:var(--lpc-round);box-shadow:2px 3px 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] .lesson-fab{background:var(--surface-solid);border-color:var(--lpc-ink);border-radius:var(--skin-wobble-btn);box-shadow:inset 0 0 0 .5px var(--lpc-ink),2px 3px 0 var(--skin-shadow-ink);backdrop-filter:none;-webkit-backdrop-filter:none;color:var(--text);transition:translate .12s ease,box-shadow .12s ease,background-color .12s ease}html[data-skin=sketchbook] .lesson-fab:nth-child(2n){border-radius:var(--skin-wobble-sm)}html[data-skin=sketchbook] .lesson-fab:hover{background:var(--skin-wash-butter);color:var(--text);translate:-1px -1px;box-shadow:inset 0 0 0 .5px var(--lpc-ink),3px 4px 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] .lesson-fab:active{translate:1px 1px;box-shadow:inset 0 0 0 .5px var(--lpc-ink),0 0 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] .lesson-fab[data-primary=true],html[data-skin=sketchbook] .lesson-fab[data-primary=true]:hover{background:color-mix(in srgb,var(--subject-tint) 20%,var(--surface-solid))}html[data-skin=sketchbook] .lesson-dock{background:var(--surface-solid);backdrop-filter:none;-webkit-backdrop-filter:none;border-color:var(--lpc-ink);border-radius:var(--skin-wobble-a);box-shadow:inset 0 0 0 .5px var(--lpc-ink),var(--shadow-1)}html[data-skin=sketchbook] .lesson-dock-btn{background:var(--surface-solid);border-color:var(--lpc-ink);border-radius:var(--lpc-round);color:var(--text);transition:background-color .12s ease,translate .12s ease}html[data-skin=sketchbook] .lesson-dock-btn.lpc-dock-text{border-radius:var(--skin-wobble-btn)}html[data-skin=sketchbook] .lesson-dock-btn:hover:not(:disabled){background:var(--skin-wash-butter);color:var(--text)}html[data-skin=sketchbook] .lesson-dock-btn:active:not(:disabled){translate:.5px 1px}html[data-skin=sketchbook] .lesson-dock-btn:is([data-on=true],[data-open=true]){background:var(--skin-wash-mist);color:var(--text)}html[data-skin=sketchbook] .lesson-dock-btn:disabled{background:transparent;border-style:dashed;border-color:var(--skin-future);opacity:.55}html[data-skin=sketchbook] .lesson-play-btn{border:var(--skin-line) solid var(--lpc-ink);border-radius:var(--lpc-round);box-shadow:2px 3px 0 var(--skin-shadow-ink);transition:translate .12s ease,box-shadow .12s ease,background-color .12s ease}html[data-skin=sketchbook] .lesson-play-btn:hover:not(:disabled){translate:-1px -1px;box-shadow:3px 4px 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] .lesson-play-btn:active:not(:disabled){translate:1px 1px;box-shadow:0 0 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] .lesson-dock-seg-bar{height:8px;background:var(--surface-solid);border:1px solid var(--lpc-ink);border-radius:3px}html[data-skin=sketchbook] .lesson-dock-seg.is-active .lesson-dock-seg-bar,html[data-skin=sketchbook] .lesson-dock-seg:hover .lesson-dock-seg-bar{height:10px}html[data-skin=sketchbook] .lesson-dock-seg[data-state=todo] .lesson-dock-seg-bar{border-style:dashed;border-color:var(--skin-future)}html[data-skin=sketchbook] .lesson-dock-seg-fill{background:var(--lpc-hatch);border-right:var(--skin-line) solid var(--lpc-ink);border-radius:0}html[data-skin=sketchbook] .lesson-dock-seg-fill.is-done,html[data-skin=sketchbook] .lesson-dock-seg-fill[style*="width: 0%"]{border-right:0}html[data-skin=sketchbook] .lesson-dock-seg-marker{background:var(--lpc-ink)}html[data-skin=sketchbook] .lesson-dock-seg-marker[data-state=answered]{background:var(--skin-future)}html[data-skin=sketchbook] :is(.lesson-speed-menu,.lesson-volume-card){background:var(--surface-solid);border-color:var(--lpc-ink);border-radius:var(--skin-wobble-sm);box-shadow:3px 4px 0 var(--skin-shadow-ink)}html[data-skin=sketchbook] .lesson-speed-opt{border-radius:8px}html[data-skin=sketchbook] .lesson-speed-opt:hover{background:var(--skin-wash-butter);color:var(--text)}html[data-skin=sketchbook] .lesson-speed-opt[data-active=true]{background:var(--skin-wash-mist)}html[data-skin=sketchbook] .lesson-speed-opt[data-active=true]:after{color:var(--text)}html[data-skin=sketchbook] .lesson-volume-mute:hover{background:var(--skin-wash-butter)}html[data-skin=sketchbook] :is(.lesson-nowplaying-back,.lesson-landscape-btn,.lesson-notice-primary,.lesson-notice-secondary,.lesson-notice-chip-btn,.lesson-volume-mute,.lesson-volume-slider,.lpc-video-fs):focus-visible{outline-style:dashed}@media (prefers-reduced-motion:reduce){html[data-skin=sketchbook] :is(.lesson-rail-open,.lesson-rail-quiz,.lesson-fab,.lesson-dock-btn,.lesson-play-btn,.lesson-notice-primary){transition:none}}.lpn-bar-title{display:flex;min-width:0;align-items:center;gap:8px}.lpn-bar-title .sk-icon{color:var(--text)}.lpn-bar-title .lesson-rail-eyebrow{min-width:0}.lpn-head{display:flex;flex-shrink:0;align-items:center;gap:10px;padding:12px 14px;border-bottom:1px solid var(--border)}.lpn-head-title{min-width:0;flex:1 1 auto;font-family:var(--font-headline);font-size:14px;font-weight:700;color:var(--text)}.lpn-lang{display:flex;flex-shrink:0;align-items:center;gap:6px}.lpn-lang,.lpn-lang-note{font-size:12px;color:var(--text-muted)}.lpn-lang-note{margin-bottom:12px;padding:6px 8px;border-radius:.375rem;line-height:1.4;background:var(--surface-2)}.lpn-empty{display:flex;flex:1 1 auto;flex-direction:column;align-items:center;justify-content:center;gap:8px;padding:32px 12px;text-align:center;color:var(--text)}.lpn-empty-text{max-width:22rem;font-size:13px;line-height:1.5;color:var(--text-muted)}.lpn-you{max-width:min(80%,22rem);padding:10px 14px;border:1px solid var(--border);border-radius:1rem 1rem .375rem 1rem;background:var(--card-glass)}.lpn-you-label{display:flex;align-items:center;gap:6px;margin-bottom:4px;font-size:11px;font-weight:600;letter-spacing:.05em;text-transform:uppercase;color:var(--text-muted)}.lpn-you-text{font-size:14px;line-height:1.625;color:var(--text)}.lpn-reply{padding:14px 16px;border:1px solid color-mix(in srgb,var(--brand) 22%,transparent);border-radius:1rem;background:var(--card-glass)}.lpn-reply-badge{display:flex;align-items:center;gap:6px;margin-bottom:10px;font-size:11px;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:color-mix(in oklab,var(--brand) 80%,var(--text))}.lpn-reply-text{font-size:15px;line-height:1.625;color:var(--text)}.lpn-reply-thinking{display:flex;align-items:center;gap:8px;margin-top:12px;font-size:12px;color:color-mix(in oklab,var(--brand) 80%,var(--text))}html[data-skin=sketchbook] .lesson-inline-panel{background-color:var(--background);background-image:radial-gradient(var(--skin-dot) 1px,transparent 1.3px);background-size:16px 16px;border-top:var(--skin-line) solid var(--skin-ink)}html.dark[data-skin=sketchbook] .lesson-inline-panel{border-top-color:var(--skin-ink-strong)}html[data-skin=sketchbook] .lesson-inline-bar{background:var(--surface-solid)}html[data-skin=sketchbook] .lesson-inline-bar-toggle{color:var(--text)}html[data-skin=sketchbook] 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