.app-shell:has(.mobile-course-workspace)>.site-header{display:none}.android-app .mobile-course-workspace{padding-bottom:calc(84px + env(safe-area-inset-bottom))}.android-app .mobile-workspace-header{z-index:20;background:var(--study-shelf);border-bottom:1px solid var(--study-shelf-line);align-items:center;gap:8px;min-height:60px;padding:6px 12px;display:flex;position:sticky;top:0}.android-app .mobile-workspace-back{min-width:44px;min-height:44px;color:var(--study-primary);background:var(--study-icon-surface);border-radius:12px;place-items:center;display:grid}.android-app .mobile-workspace-course{text-align:left;min-width:0;min-height:48px;font:inherit;color:var(--study-ink);background:0 0;border:0;border-radius:12px;flex:1;justify-content:space-between;align-items:center;gap:10px;padding:4px 8px;display:flex}.android-app .mobile-workspace-course>span{min-width:0}.android-app .mobile-workspace-course strong{overflow-wrap:anywhere;font-size:14px;line-height:1.3;display:block}.android-app .mobile-workspace-course small{color:var(--study-muted);font-size:11px;display:block}.android-app .mobile-workspace-course>svg{color:var(--study-primary);flex-shrink:0}.android-app .mobile-course-tabs{z-index:30;width:100%;max-width:520px;padding:7px 12px calc(8px + env(safe-area-inset-bottom));background:var(--study-shelf);border-top:1px solid var(--study-shelf-line);grid-template-columns:repeat(3,minmax(0,1fr));gap:5px;display:grid;position:fixed;bottom:0;left:50%;transform:translate(-50%);box-shadow:0 -4px 16px #41276b08}.android-app .mobile-course-tabs>a{min-height:56px;color:var(--study-muted);border-radius:14px;flex-direction:column;justify-content:center;align-items:center;gap:3px;font-size:12px;text-decoration:none;display:flex}.android-app .mobile-course-tabs>a[aria-current=page]{color:var(--study-primary);background:var(--study-soft);font-weight:600}.android-app .mobile-course-tab-icon{place-items:center;display:grid}.android-app .mobile-course-tabs>a:focus-visible,.android-app .mobile-workspace-course:focus-visible,.android-app .mobile-workspace-back:focus-visible{outline:2px solid var(--study-primary);outline-offset:2px}.android-app .mobile-course-switcher{width:calc(100% - 28px);max-width:440px;max-height:calc(var(--native-viewport-height,100dvh) * .8);border:1px solid var(--study-shelf-line);color:var(--study-ink);background:#fff;border-radius:22px;padding:18px}.android-app .mobile-course-choices{gap:10px;display:grid}.android-app .mobile-course-choices>a{border:1px solid var(--study-shelf-line);min-height:56px;color:var(--study-ink);background:var(--study-shelf);border-radius:13px;justify-content:space-between;align-items:center;gap:12px;padding:12px;font-size:14px;text-decoration:none;display:flex}.android-app .mobile-course-choices>a>svg{color:var(--study-primary);flex-shrink:0}.android-app .mobile-course-choices>.mobile-course-choices-all{color:var(--study-primary);background:0 0;border-color:#0000}.android-app .mobile-ai-tools-panel:not([hidden]){background:var(--study-shelf);border:1px solid var(--study-shelf-line);border-radius:16px;margin:6px 10px 8px;padding:2px 10px 8px;box-shadow:0 3px 10px #41276b08}.android-app .mobile-ai-tools-panel>p{color:var(--study-muted);margin:7px 2px 0;font-size:11px;line-height:1.4}.android-app .reading-sheet .learning-document{font-size:var(--study-copy-font,1rem);line-height:var(--lesson-line-height,1.65);-webkit-user-select:text;user-select:text;-webkit-touch-callout:none}.android-app .reading-sheet[data-word-selection=true] .learning-document{-webkit-user-select:none;user-select:none;-webkit-touch-callout:none}.android-app .mobile-word-selection-bar{background:0 0;border-radius:10px;flex-wrap:wrap;align-items:center;gap:8px;padding:0;font-size:12px;display:flex}.android-app .mobile-word-selection-info{flex:1;gap:2px;min-width:0;display:grid}.android-app .mobile-word-selection-info strong{color:var(--study-ink);font-size:12px;font-weight:600}.android-app .mobile-word-selection-info [role=status]{color:var(--study-muted);font-size:11px;line-height:1.4}.android-app .mobile-word-selection-symbol{background:var(--study-soft);width:32px;height:32px;color:var(--study-primary);border-radius:10px;flex-shrink:0;place-items:center;display:grid}.android-app .mobile-word-selection-bar button{min-width:48px;min-height:48px;color:var(--study-primary);font:inherit;background:0 0;border:0;border-radius:8px;padding:6px}.android-app .mobile-word-selection-bar .mobile-word-selection-cancel{background:var(--study-icon-surface);color:var(--study-muted);border:1px solid var(--study-shelf-line);border-radius:14px;flex-shrink:0;place-items:center;display:grid}.android-app .mobile-word-selection-cancel:hover{background:var(--study-track)}.android-app .mobile-word-fine-controls{border-top:1px solid var(--study-shelf-line);border-bottom:1px solid var(--study-shelf-line);justify-content:space-between;align-items:center;gap:3px;width:100%;margin-bottom:4px;padding:2px 0;display:flex}.android-app .mobile-word-adjustment-label{min-width:0;color:var(--study-muted);flex:1;font-size:11px}.android-app .mobile-word-selection-actions{flex-shrink:0;grid-template-columns:repeat(3,minmax(0,1fr));align-items:stretch;gap:6px;padding:0;display:grid}.android-app .mobile-word-selection-actions[data-action-count="2"]{grid-template-columns:repeat(2,minmax(0,1fr))}.android-app .mobile-word-selection-actions>button,.android-app .mobile-selection-actions>button{border:1px solid var(--study-nav-line);width:100%;min-width:0;min-height:48px;box-shadow:none;color:var(--study-ink);white-space:nowrap;background:#fff;border-radius:12px;justify-content:center;gap:6px;padding:10px 8px;font-size:13px;font-weight:600;line-height:1.35}.android-app .mobile-word-selection-actions>.revision-explain-button,.android-app .mobile-selection-actions>.revision-explain-button{background:var(--study-primary);border-color:var(--study-primary);color:var(--study-on-primary)}.android-app .mobile-word-selection-actions>.revision-teach-button,.android-app .mobile-selection-actions>.revision-teach-button{background:var(--study-icon-surface);border-color:var(--study-nav-line);color:var(--study-primary)}.android-app .mobile-word-selection-actions>.revision-save-button,.android-app .mobile-selection-actions>.revision-save-button{background:var(--study-save-surface);color:var(--study-save-ink);border-color:#eaacc3}.android-app .mobile-word-selection-actions>.revision-explain-button:hover:not(:disabled),.android-app .mobile-selection-actions>.revision-explain-button:hover:not(:disabled){background:var(--study-primary-hover)}.android-app .mobile-word-selection-actions>.revision-teach-button:hover:not(:disabled),.android-app .mobile-selection-actions>.revision-teach-button:hover:not(:disabled){background:var(--study-soft)}.android-app .mobile-word-selection-actions>.revision-save-button:hover:not(:disabled),.android-app .mobile-selection-actions>.revision-save-button:hover:not(:disabled){background:var(--study-save-hover)}.android-app .mobile-word-selection-actions>button:disabled,.android-app .mobile-selection-actions>button:disabled{background:var(--study-track);border-color:var(--study-shelf-line);color:var(--study-muted);opacity:1}.android-app .mobile-word-selection-actions>button:focus-visible,.android-app .mobile-selection-actions>button:focus-visible,.android-app .mobile-word-selection-bar button:focus-visible,.mobile-word-handle:focus-visible{outline:2px solid var(--study-primary,#6442a6);outline-offset:2px}.mobile-word-selection-overlay{z-index:35;pointer-events:none;position:fixed;inset:0}.mobile-word-highlight{background:#9870eb38;border-radius:2px;position:absolute}.mobile-word-handle{pointer-events:auto;touch-action:none;background:0 0;border:0;width:48px;height:48px;padding:0;position:absolute}.mobile-word-handle>span{background:#7548d8;border:2px solid #fff;border-radius:50%;width:18px;height:18px;position:absolute;top:3px;left:15px;box-shadow:0 1px 4px #42247a22}.mobile-word-handle:before{content:"";background:#7548d8;width:2px;height:15px;position:absolute;top:0;left:23px}.mobile-word-handle--start:before{top:15px}.mobile-word-loupe{color:#372841;text-align:center;text-overflow:ellipsis;white-space:nowrap;background:#fff;border:1px solid #e0d5f2;border-radius:12px;width:170px;padding:12px;font-size:20px;position:absolute;overflow:hidden;box-shadow:0 4px 20px #32195125}.app-shell:has(.android-app){background:#faf9ff}:is(.app-shell:has(.android-app) .site-footer,.app-shell:has(.android-app) .header-default-actions){display:none}.app-shell:has(.android-app) .header-inner{max-width:520px;height:58px;min-height:58px;padding:10px 16px}.app-shell:has(.android-app) .header-revision-label{display:none}.app-shell:has(.android-app) .header-revision-label-short{display:inline}.app-shell:has(.android-app) .header-revision-button.button{min-height:38px;padding:8px 9px;font-size:11px}.app-shell:has(.android-app) .header-navigation{gap:9px}.app-shell:has(.android-app) .brand{font-size:16px}.android-app{width:100%;min-width:0;max-width:520px;margin:auto}.android-app .page-container{padding:24px 18px 36px}.android-app .library-welcome p{color:#70687e;margin:12px 0 20px;font-size:14px;line-height:1.6}.android-app .search-field{width:100%;margin-bottom:24px}.android-app .course-grid{grid-template-columns:minmax(0,1fr)}.android-app .library-page .course-card{grid-template-columns:88px minmax(0,1fr);gap:16px;min-height:0;padding:18px;display:grid}.android-app .course-card .course-cover,.android-app .course-card .course-artwork{width:88px;height:108px}.android-app .library-page .course-card h3{font-size:18px}.android-app .library-page .course-card p{margin-bottom:14px;font-size:13px}.android-app .course-hero{grid-template-columns:minmax(0,1fr) 76px;gap:16px;padding:20px}.android-app .course-hero h1{font-size:26px}.android-app .course-hero .course-cover,.android-app .course-hero .course-artwork{width:76px;height:90px}.android-app .course-intro{font-size:13px;line-height:1.6}.android-app .tutor-entry-card{min-height:0;margin:20px 0 28px;padding:22px}.android-app .card-topline h2{font-size:23px}.android-app .tutor-entry-card p{font-size:14px;line-height:1.6}.android-app .tutor-resume-action{width:100%;min-height:68px;padding:15px}.android-app .tutor-explore-link{width:100%;min-height:48px;margin-top:12px}.android-app .mobile-chapter-picker{scroll-margin-top:16px}.android-app .mobile-chapter-picker h2{margin:0 0 16px;font-size:19px}.android-app .chapter>summary{padding:18px 14px}.android-app .chapter-body{padding:0 12px 16px}.android-app .subtopic-link{min-height:54px;padding:14px 12px}.android-app .mobile-course-overview{gap:12px;max-width:420px;margin-inline:auto;padding:14px 16px;display:grid}.android-app .mobile-course-overview .course-hero{border-radius:18px;grid-template-columns:minmax(0,1fr) 58px;align-items:start;gap:10px 12px;margin:0;padding:14px}.android-app .mobile-course-overview .course-hero h1{margin:0 0 5px;font-size:22px;line-height:1.25}.android-app .mobile-course-overview .course-intro{margin:0;font-size:12px;line-height:1.45}.android-app .mobile-course-overview .course-cover,.android-app .mobile-course-overview .course-art,.android-app .mobile-course-overview .course-artwork{border-radius:12px;width:58px;height:66px}.android-app .mobile-course-overview .course-progress{background:0 0;border:0;grid-column:1/-1;margin:0;padding:0;font-size:12px}.android-app .mobile-course-overview .course-progress>div{gap:4px 8px;font-size:12px}.android-app .mobile-course-overview .course-progress span{font-size:11px}.android-app .mobile-course-overview .course-progress progress{height:5px;margin-top:6px}.android-app .mobile-course-overview .tutor-entry-card{aspect-ratio:auto;justify-content:flex-start;gap:16px;min-height:min-content;margin:0;padding:18px}.android-app .mobile-course-overview .card-topline{gap:10px;margin-bottom:10px}.android-app .mobile-course-overview .card-topline .tile-icon{border-radius:12px;width:38px;height:38px}.android-app .mobile-course-overview .tutor-entry-card h2{font-size:24px}.android-app .mobile-course-overview .tutor-entry-card p{margin:0;font-size:13px;line-height:1.5}.android-app .mobile-course-overview .mobile-tutor-entry-actions{gap:8px;display:grid}.android-app .mobile-course-overview .tutor-resume-action,.android-app .mobile-course-overview .tutor-explore-link{border-radius:12px;align-items:center;gap:12px}.android-app .mobile-course-overview .tutor-resume-action{min-height:64px;padding:12px 14px}.android-app .mobile-course-overview .tutor-action-copy strong{font-size:14px;line-height:1.35}.android-app .mobile-course-overview .tutor-action-copy>span{font-size:12px;line-height:1.45}.android-app .mobile-course-overview .tutor-explore-link{min-height:72px;margin-top:0;padding:16px 14px;font-size:14px}.android-app .mobile-course-overview .tutor-explore-label{flex:1;min-width:0}.android-app .mobile-chapter-picker h1{margin:0 0 12px;font-size:23px;line-height:1.3}.android-app .mobile-chapter-picker .selector-meta{flex-wrap:wrap;gap:6px 12px;font-size:13px}.android-app .mobile-chapter-picker .chapter-summary strong{font-size:15px}.android-app .chapter-progress-percent,.android-app .topic-progress-percent{color:#176644;background:#edf5f0;border-radius:8px;flex-shrink:0;padding:4px 7px;font-size:12px;font-weight:600}.android-app .mobile-course-collection .collection-heading{margin-bottom:20px}.android-app .mobile-course-collection .collection-heading h1{margin:8px 0;font-size:24px}.android-app .mobile-course-collection .collection-heading>p:last-of-type{font-size:13px;line-height:1.5}.android-app .mobile-course-collection .collection-heading .tile-icon{width:38px;height:38px;margin-bottom:10px}@media (max-height:760px){.android-app .mobile-course-overview{gap:10px;padding-block:10px}.android-app .mobile-course-overview .tutor-entry-card{padding:16px}}.app-shell:has(.android-app .learning-page)>#main-content>.android-app{max-width:520px;height:100%}.android-app .learning-page{--spoken-text-surface:#f3edf9;--spoken-text-outline:none;--spoken-text-radius:2px;max-width:900px;padding-inline:10px}.android-app .learning-page .reading-sheet{border-radius:14px;padding:22px 18px 30px}.android-app .learning-page .learning-scroll-region{padding:12px 0}.android-app .component-image.explicit-media-width-full .media-leaf img{max-height:clamp(220px, calc(var(--native-viewport-height,100dvh) * .8), 800px)}.android-app .table-scroll{--mobile-table-cell-padding:12px;--mobile-table-leading:1.65;max-height:clamp(160px, calc(var(--native-viewport-height,100dvh) * .65), 560px);scrollbar-width:thin;scrollbar-color:#b6a3c9 #f6f2fa;font-size:max(1rem,.95em)}.android-app .table-scroll table{border-collapse:separate;border-spacing:0;line-height:var(--mobile-table-leading)}.android-app .table-scroll th,.android-app .table-scroll td{padding:var(--mobile-table-cell-padding)}.android-app .table-scroll thead{z-index:3;position:sticky;top:0}.android-app .table-scroll th{color:#4e316c;background:#f0e8f7}.android-app .table-scroll tbody tr:nth-child(2n)>td{background:#faf8fc}.android-app .table-scroll--dense:not([data-pin-first-column]) :is(th,td):first-child{box-shadow:none;position:static}.android-app .table-scroll[data-pin-first-column] :is(th,td):first-child{z-index:1;color:#4e316c;background:#f6f1fa;position:sticky;left:0;box-shadow:2px 0 #ded3e8}.android-app .table-scroll[data-pin-first-column] thead th:first-child{z-index:4;background:#eee4f6}.android-app .table-scroll tr[data-teaching-current=true]>:is(th,td){background:var(--spoken-text-surface,#f3edf9)}.android-app .table-scroll tr:is(.revision-row-selected,.revision-row-context)>:is(th,td){background:#f3edfc}.android-app .learning-page .lesson-title{font-size:27px;line-height:1.3}.android-app .learning-page .reading-context{margin-bottom:18px}.android-app .learning-page .reading-breadcrumb{gap:5px;font-size:11px}.android-app .learning-page .teaching-toolbar{padding:10px 2px 8px}.android-app .teaching-toolbar-actions{flex-wrap:wrap;justify-content:space-between;gap:8px}.android-app .learning-page .teaching-hint{margin-top:8px;font-size:10px;line-height:1.45}.android-app .learning-page[data-learning-mode=reading] .teaching-preferences{display:none}.android-app .learning-navigation{padding-block:8px}.android-app .learning-navigation-inner,.android-app .learning-navigation--with-doubts .learning-navigation-inner{grid-template-columns:minmax(0,1fr) minmax(0,1.1fr) minmax(0,1fr);gap:8px}.android-app .learning-navigation--without-playback .learning-navigation-inner,.android-app .learning-navigation--with-doubts.learning-navigation--without-playback .learning-navigation-inner{grid-template-columns:repeat(2,minmax(0,1fr))}.android-app .learning-navigation-question{grid-area:1/1/auto/-1}.android-app .page-nav{border-radius:12px;min-height:54px;padding:10px}.android-app .page-nav small{font-size:9px}.android-app .page-nav strong{font-size:11px;line-height:1.4}.android-app .page-nav-icon{display:none}.android-app textarea,.android-app input{font-size:16px}.android-app .learning-navigation .teaching-pause--tile{border-radius:12px;min-width:68px;min-height:54px;padding:8px}.android-app .skip-component{bottom:180px}.android-app .doubt-workspace[data-open=true]{grid-template-columns:minmax(0,1fr)}.android-app .doubt-workspace[data-open=true] .doubt-lesson-column,.android-app .doubt-divider{display:none}.android-app .learning-page:has(.doubt-workspace[data-open=true]) .learning-sticky-controls{display:none}.android-app .learning-page:has(.doubt-workspace[data-open=true]){grid-template-rows:minmax(0,1fr)}.android-app .doubt-panel[data-layout=compact]{z-index:40;width:min(100%,520px);max-height:var(--native-viewport-height,100dvh);--study-primary:var(--study-toolbar-accent,#7040a6);--study-primary-hover:#60338f;--study-soft:#f3edf9;--study-nav-line:#e2dbea;--study-ink:#4e316c;--study-muted:#685676;--study-on-primary:#fff;--study-track:#e0cbf1;min-height:0;height:var(--native-viewport-height,100dvh);border-radius:14px 14px 0 0;margin:0 auto;position:fixed;inset:0}.android-app .doubt-panel[data-layout=compact] .doubt-panel-heading{flex-wrap:wrap;flex-shrink:0;gap:6px;padding:6px 10px}.android-app .doubt-panel[data-layout=compact] .doubt-panel-heading h2{min-width:0;font-size:14px;line-height:20px}.android-app .doubt-panel[data-layout=compact] .lesson-mode-switch button{min-width:48px;min-height:48px;padding:6px 8px;font-size:12px;line-height:1.25}.android-app .doubt-panel[data-layout=compact] .doubt-panel-heading>.teaching-pause{flex-basis:48px;width:48px;min-width:48px;height:48px;min-height:48px}.android-app .doubt-conversation{padding:20px 16px}.android-app .doubt-panel[data-layout=compact] :is(.doubt-whiteboard .learning-document,.doubt-context-document .learning-document,.doubt-context>p,.doubt-student-question){font-size:var(--study-copy-font,1rem);line-height:var(--lesson-line-height,1.65)}.android-app .doubt-panel[data-layout=compact] :is(.doubt-student-question>span,.doubt-answer-label,.doubt-context summary){font-size:12px;line-height:1.4}.android-app .doubt-panel[data-layout=compact] [data-composer][data-composer-interaction=chat] textarea::placeholder{font-size:16px}.android-app .doubt-panel[data-layout=compact] .doubt-panel-footer{padding:10px 12px calc(10px + env(safe-area-inset-bottom));flex-shrink:0}:is(.android-app .doubt-panel-footer:has(textarea:focus) .doubt-lesson-return,.android-app .doubt-panel-footer:has([data-voice-busy=true]) .doubt-lesson-return){display:none}.android-app .doubt-panel[data-layout=compact] .doubt-lesson-return{grid-template-columns:minmax(0,1fr) minmax(0,1fr);align-items:center}.android-app .doubt-panel[data-layout=compact] .doubt-save-conversation,.android-app .doubt-panel[data-layout=compact] .doubt-continue{justify-self:stretch;min-height:48px;padding:8px;font-size:13px}.android-app .doubt-panel[data-layout=compact] .doubt-lesson-return svg{flex-shrink:0}.android-app .checkpoint-sheet{padding:20px 12px}.android-app .question-card-header{flex-wrap:wrap}.android-app .learning-enrichment-card{--enrichment-body-size:var(--study-copy-font,1rem);--enrichment-title-size:1.125rem;font-size:var(--enrichment-body-size);border-radius:12px;margin-block:16px;line-height:1.6}.android-app .learning-enrichment-header{border-radius:11px 11px 0 0;padding:8px 12px}.android-app .learning-enrichment-toolbar{grid-template-columns:minmax(0,1fr) 48px;gap:8px 10px;margin-bottom:4px;display:grid}.android-app .learning-enrichment-toolbar:not(:has(.revision-save-button)){grid-template-columns:minmax(0,1fr)}.android-app .learning-enrichment-heading{gap:7px}.android-app .learning-enrichment-label{letter-spacing:.05em;overflow-wrap:anywhere;font-size:.75rem;line-height:1.4}.android-app .learning-enrichment-card .component-heading :is(h1,h2,h3){font-size:var(--enrichment-title-size);margin:0;line-height:1.4}.android-app .learning-enrichment-card .component-heading .size-heading{font-size:inherit}.android-app .learning-enrichment-body{font-size:var(--enrichment-body-size);border-radius:0 0 11px 11px;gap:10px;padding:0 12px 12px;line-height:1.6}.android-app .learning-enrichment-card .learning-document{font-size:inherit;line-height:inherit}.android-app .learning-enrichment-card .size-small{font-size:var(--study-small-font,.875rem)}.android-app .learning-enrichment-card .source-list{gap:8px}.android-app .learning-enrichment-card[data-enrichment-type=key_points] .source-list{gap:0}.android-app .learning-enrichment-card[data-enrichment-type=key_points] .source-list li{line-height:1.6}.android-app .learning-enrichment-card .enrichment-points>li{padding-bottom:8px}.android-app .learning-enrichment-card .enrichment-points>li:last-child{padding-bottom:0}.android-app .learning-enrichment-card:is([data-enrichment-type=memory_aid],[data-enrichment-type=real_world_connection]) :is(.learning-enrichment-body,.source-list){grid-template-columns:minmax(0,1fr);gap:8px}.android-app .learning-enrichment-card:is([data-enrichment-type=memory_aid],[data-enrichment-type=real_world_connection]) .learning-enrichment-body :is(.component-paragraph,.source-list li){border-radius:8px;padding:8px 10px}.android-app .learning-enrichment-card[data-enrichment-type=formula_essentials] .learning-enrichment-body{gap:14px}.android-app .learning-enrichment-card[data-enrichment-type=formula_essentials] .component-formula{gap:9px}.android-app .learning-enrichment-card[data-enrichment-type=formula_essentials] .formula-leaf{font-size:var(--lesson-font-size,1rem);border-radius:8px;padding:8px 12px}.android-app .learning-enrichment-card[data-enrichment-type=formula_essentials] .math-expression .katex{font-size:var(--study-math-scale,1.25em)}.android-app .learning-enrichment-card .enrichment-formula-caption{font-size:var(--study-caption-font,.875rem);line-height:1.5}.android-app .learning-enrichment-card[data-enrichment-type=formula_essentials] .learning-enrichment-body .component-paragraph{font-size:var(--enrichment-body-size);line-height:1.6}.android-app .learning-enrichment-card[data-enrichment-type=prerequisite_refresher] .learning-enrichment-body{margin:2px 14px 14px;padding:0 0 0 12px}.android-app .learning-enrichment-card[data-enrichment-type=conditions_and_exceptions] .learning-enrichment-body .component-paragraph{padding:8px 12px}.android-app :is(.learning-enrichment-toolbar,.practice-card-heading-actions) .revision-save-button{isolation:isolate;background:0 0;border:0;flex:0 0 48px;width:48px;min-width:48px;min-height:48px;padding:0;position:relative}.android-app :is(.learning-enrichment-toolbar,.practice-card-heading-actions) .revision-save-button:before{content:"";z-index:-1;pointer-events:none;background:#fff;border:1px solid #ddd3eb;border-radius:8px;position:absolute;inset:8px}.android-app :is(.learning-enrichment-toolbar,.practice-card-heading-actions) .revision-save-button.is-saved:before{background:#eff8f2;border-color:#a9d3bc}.android-app .learning-enrichment-card.is-revision-saved .learning-enrichment-revision.is-saved{background:0 0}.android-app .learning-enrichment-card.is-revision-saved .learning-enrichment-revision.is-saved:before{background:#2563eb;border-color:#2563eb}.android-app .learning-enrichment-card.is-revision-saved .learning-enrichment-revision:hover:not(:disabled):before{background:#1d4ed8}.android-app :is(.learning-enrichment-toolbar,.practice-card-heading-actions) .revision-save-button:hover:not(:disabled):before{border-color:currentColor}.android-app :is(.learning-enrichment-toolbar,.practice-card-heading-actions) .revision-save-button:focus-visible{outline-offset:1px;outline:2px solid}.android-app :is(.learning-enrichment-toolbar,.practice-card-heading-actions) .revision-save-button>svg{width:16px;height:16px}.android-app .learning-enrichment-toolbar .revision-save-button:before{inset:4px}.android-app .learning-enrichment-toolbar .revision-save-button:not(.is-saved):before{background:0 0;border:0}.android-app .learning-enrichment-toolbar .revision-save-button>svg{width:18px;height:18px}.android-app :is(.learning-enrichment-toolbar,.practice-card-heading-actions) .revision-save-button>span{clip-path:inset(50%);white-space:nowrap;width:1px;height:1px;position:absolute;overflow:hidden}.android-app .checkpoint-page{--checkpoint-body-size:.875rem;--checkpoint-title-size:1rem;--checkpoint-label-size:.75rem;--checkpoint-card-label-size:.6875rem;--checkpoint-body-leading:1.5}.android-app .checkpoint-page .checkpoint-titlebar{gap:6px 12px;padding-block:12px}.android-app .checkpoint-page .checkpoint-title{font-size:var(--checkpoint-title-size);line-height:var(--checkpoint-body-leading)}.android-app .checkpoint-page .checkpoint-titlebar .reading-breadcrumb{min-width:0;font-size:var(--checkpoint-label-size);line-height:var(--checkpoint-body-leading);flex-basis:100%}.android-app .checkpoint-page .checkpoint-sheet{padding:14px 10px}.android-app .checkpoint-page .checkpoint-items{gap:16px}.android-app .checkpoint-page .practice-card{--question-space:14px;font-size:var(--checkpoint-body-size);line-height:var(--checkpoint-body-leading);padding:14px}.android-app .checkpoint-page .practice-card-heading{grid-template-columns:26px minmax(0,1fr) 48px;align-items:center;gap:6px;margin-bottom:10px;display:grid}.android-app .checkpoint-page .question-card .practice-card-heading{padding-block:6px}.android-app .checkpoint-page .practice-icon{border-radius:8px;flex-basis:26px;height:26px}.android-app .checkpoint-page .practice-icon svg{width:16px;height:16px}.android-app .checkpoint-page .practice-card-title{grid-area:1/2;min-width:0}.android-app .checkpoint-page .practice-card-heading-actions{display:contents}.android-app .checkpoint-page .practice-card-heading .revision-save-button{grid-area:1/3}.android-app .checkpoint-page .practice-card-heading:has(.question-attempted) :is(.practice-icon,.revision-save-button){grid-row:1/span 2}.android-app .checkpoint-page .question-attempted{font-size:var(--checkpoint-card-label-size);grid-area:2/2}.android-app .checkpoint-page .practice-card-heading h2,.android-app .checkpoint-page .component-heading h1,.android-app .checkpoint-page .component-heading h2,.android-app .checkpoint-page .component-heading h3{font-size:var(--checkpoint-title-size);line-height:var(--checkpoint-body-leading);margin-block:0 8px}.android-app .checkpoint-page .practice-card-heading h2{margin:0}.android-app .checkpoint-page .practice-card-label,.android-app .checkpoint-page .practice-card-heading h2.practice-card-label{font-size:var(--checkpoint-card-label-size);letter-spacing:.03em;line-height:1.4}.android-app .checkpoint-page .practice-card .learning-document{font-size:var(--checkpoint-body-size);line-height:var(--checkpoint-body-leading)}.android-app .checkpoint-page .learning-document .size-heading{font-size:var(--checkpoint-title-size)}.android-app .checkpoint-page .content-component{margin-bottom:14px}.android-app .checkpoint-page .content-component:last-child{margin-bottom:0}.android-app .checkpoint-page .source-list{gap:8px;padding-inline-start:0}.android-app .checkpoint-page .source-list li{grid-template-columns:1.5em minmax(0,1fr)}.android-app .checkpoint-page .source-list-marker{padding-inline-end:6px}.android-app .checkpoint-page .formula-leaf{padding-block:4px;font-size:1rem}.android-app .checkpoint-page .question-options{grid-template-columns:minmax(0,1fr);gap:8px;margin-block:16px}.android-app .checkpoint-page .question-options legend,.android-app .checkpoint-page .activity-recall-cue,.android-app .checkpoint-page .question-discussion-heading span,.android-app .checkpoint-page .doubt-answer-label{font-size:var(--checkpoint-label-size);line-height:var(--checkpoint-body-leading)}.android-app .checkpoint-page .question-option{grid-template-columns:16px minmax(0,1fr);gap:6px;min-height:48px;padding:10px 8px}.android-app .checkpoint-page .question-option input{margin-top:4px}.android-app .checkpoint-page .option-letter{width:24px;height:24px}.android-app .checkpoint-page .practice-solution{gap:16px;margin-top:16px;padding-top:16px}.android-app .checkpoint-page .practice-response{padding-inline-start:12px}.android-app .checkpoint-page .practice-response--mint{padding:12px}.android-app .checkpoint-page .practice-response-heading{flex-wrap:wrap;margin-bottom:8px}.android-app .checkpoint-page .practice-response h3,.android-app .checkpoint-page .question-discussion-heading h3,.android-app .checkpoint-page .doubt-student-question,.android-app .checkpoint-page .question-feedback,.android-app .checkpoint-page .practice-error{font-size:var(--checkpoint-body-size);line-height:var(--checkpoint-body-leading)}.android-app .checkpoint-page .activity-reveal-body{margin-top:12px;padding:12px}.android-app .checkpoint-page .activity-visible-explanation{margin-top:14px;padding-top:14px}.android-app .checkpoint-page .question-discussion{margin-top:18px;padding-top:14px}.android-app .checkpoint-page .question-discussion-heading{flex-wrap:wrap;gap:6px;margin-bottom:12px}.android-app .checkpoint-page .question-actions{gap:8px;margin-top:16px}.android-app .checkpoint-page .question-actions .button,.android-app .checkpoint-page .activity-reveal-toggle{min-width:48px;min-height:48px;font-size:var(--checkpoint-body-size)}:is(.app-shell:has(.mobile-study-controls),.android-app){--study-shelf:#f2eff3;--study-shelf-line:#d0cdd7;--study-ink:#402060;--study-muted:#65636d;--study-primary:#6442a6;--study-primary-hover:#55358f;--study-on-primary:#fff;--study-track:#eae7ec;--study-ai:#6442a6;--study-soft:#f2e2fc;--study-previous:#faf9fb;--study-previous-hover:#eae7ec;--study-next:#ead5f9;--study-next-hover:#e0c4f4;--study-nav-ink:#402060;--study-nav-line:#d1afec;--study-nav-hover-line:#be93e4;--study-icon-surface:#fdfcfd;--study-save-surface:#ffe9f0;--study-save-hover:#ffdce8;--study-save-ink:#621639;--study-mcq-surface:#f7edfe;--study-mcq-ink:#402060;--study-written-surface:#fef7f9;--study-written-ink:#621639;--study-visual-surface:#fbebfb;--study-visual-ink:#53195d;--study-refresher-surface:#f1f0ef;--study-refresher-ink:#63635e}.android-app .checkpoint-page .checkpoint-sheet{border-top-color:var(--study-nav-line)}.android-app .checkpoint-page .practice-card{border-color:color-mix(in srgb, var(--practice-accent) 20%, #fff);border-radius:16px;box-shadow:0 3px 10px #40206006}.android-app .checkpoint-page .question-card--mcq{--practice-tint:var(--study-mcq-surface);--practice-accent:var(--study-mcq-ink)}.android-app .checkpoint-page .question-card--subjective{--practice-tint:var(--study-written-surface);--practice-accent:var(--study-written-ink)}.android-app .checkpoint-page .question-option:not(.question-option--correct):not(.question-option--incorrect){background:var(--study-icon-surface);border-color:var(--study-shelf-line)}.android-app .checkpoint-page .question-option:not(.question-option--correct):not(.question-option--incorrect):hover{background:var(--study-mcq-surface);border-color:var(--study-nav-hover-line)}.android-app .checkpoint-page .question-option--selected:not(.question-option--correct):not(.question-option--incorrect){background:var(--study-soft);border-color:var(--study-primary);box-shadow:inset 0 0 0 1px var(--study-primary)}.android-app .checkpoint-page .question-option:focus-within{outline-color:var(--study-primary)}.android-app .checkpoint-page .question-option input{accent-color:var(--study-primary)}.android-app .checkpoint-page .question-option:not(.question-option--correct):not(.question-option--incorrect) .option-letter{background:var(--study-track);color:var(--study-ink)}.android-app .checkpoint-page .question-option--selected:not(.question-option--correct):not(.question-option--incorrect) .option-letter{background:var(--study-primary);color:var(--study-on-primary)}.android-app .checkpoint-page .question-actions .button--secondary{color:var(--study-ink);border-color:var(--study-shelf-line);background:var(--study-icon-surface)}.android-app .checkpoint-page .question-actions .button--secondary:hover:not(:disabled){background:var(--study-track)}.android-app .checkpoint-page .question-actions .button--primary{color:var(--study-on-primary);border-color:var(--study-primary);background:var(--study-primary)}.android-app .checkpoint-page .question-actions .button--primary:hover:not(:disabled){background:var(--study-primary-hover)}.android-app .checkpoint-page .practice-response{border-left-color:var(--study-nav-line)}.android-app .checkpoint-page .practice-response--mint{background:var(--study-icon-surface);border-color:var(--study-shelf-line);border-left-color:var(--study-nav-hover-line)}.android-app .checkpoint-page .practice-response--mint h3{color:var(--study-ink)}.android-app .checkpoint-page .activity-visible-explanation{border-top-color:var(--study-shelf-line)}.app-shell:has(.mobile-study-controls) .site-header{background:var(--study-track);border-bottom-color:var(--study-shelf-line);box-shadow:0 2px 10px #4020600d}.app-shell:has(.mobile-conversation-controls) .site-header{display:none}.app-shell:has(.mobile-study-controls) .header-navigation{display:none}.app-shell:has(.mobile-study-controls) .header-inner{height:52px;min-height:52px;padding:0 10px}.app-shell:has(.mobile-study-controls) .header-actions-group{flex:1;grid-column:1/-1;min-width:0}.app-shell:has(.mobile-study-controls) .page-header-actions{width:100%;min-width:0}.mobile-study-controls{align-items:center;gap:2px;width:100%;display:flex}.mobile-study-icon{isolation:isolate;width:48px;height:48px;color:var(--study-ink);background:0 0;border:0;border-radius:10px;flex-shrink:0;justify-content:center;align-items:center;display:inline-flex;position:relative}.mobile-study-icon:not(.mobile-study-ai):before{content:"";z-index:-1;pointer-events:none;border:1px solid var(--study-shelf-line);background:var(--study-icon-surface);border-radius:11px;position:absolute;inset:7px 5px;box-shadow:0 2px 3px #40206008}.mobile-study-save{color:var(--study-save-ink);margin-left:auto}.mobile-study-save.mobile-study-icon:before{background:var(--study-save-surface);border-color:#eaacc3}.mobile-study-controls:has(.mobile-study-ai) .mobile-study-save{margin-left:0}.mobile-study-ai{width:0;min-width:48px;color:var(--study-on-primary);font:inherit;white-space:nowrap;flex:1 1 0;padding:0 4px;font-size:12px;font-weight:600}.mobile-study-ai .mobile-study-ai-chip{border:1px solid var(--study-shelf-line);background:var(--study-icon-surface);color:var(--study-primary);border-radius:11px;align-items:center;gap:4px;padding:7px;display:inline-flex}.mobile-study-ai .mobile-study-ai-label-short{display:none}.mobile-study-ai[aria-pressed=true] .mobile-study-ai-chip{background:var(--study-primary-hover);border-color:var(--study-primary-hover);color:var(--study-on-primary);box-shadow:0 0 0 2px var(--study-on-primary)}.mobile-study-icon:focus-visible{outline:2px solid var(--study-primary);outline-offset:-2px}.mobile-study-icon:not(.mobile-study-ai):hover:not(:disabled){color:var(--study-primary)}.mobile-study-icon:not(.mobile-study-ai):hover:not(:disabled):before,.mobile-study-icon[aria-haspopup=dialog][aria-expanded=true]:before{background:var(--study-soft);border-color:var(--study-nav-hover-line)}.mobile-study-ai:hover:not(:disabled) .mobile-study-ai-chip{border-color:var(--study-primary)}.mobile-study-save-count{border:2px solid var(--study-track);background:var(--study-save-ink);color:#fff;border-radius:10px;min-width:16px;padding:1px 3px;font-size:9px;font-weight:700;line-height:12px;position:absolute;top:3px;right:2px}.mobile-study-icon:disabled{opacity:.5}.mobile-study-mode-toggle{isolation:isolate;flex:none;width:128px;height:48px;position:relative}.mobile-study-mode-toggle:before,.mobile-study-mode-toggle:after{content:"";pointer-events:none;border-radius:999px;position:absolute}.mobile-study-mode-toggle:before{background:var(--study-track);border:1px solid var(--study-shelf-line);inset:7px 0;box-shadow:inset 0 1px 2px #4020600a}.mobile-study-mode-toggle:after{background:var(--study-on-primary);width:calc(50% - 3px);transition:transform .18s;top:10px;bottom:10px;left:3px;box-shadow:0 1px 4px #4a326019}.mobile-study-mode-toggle[data-mode=tutor]:after{transform:translate(100%)}.mobile-study-mode-toggle .lesson-mode-switch{z-index:1;box-sizing:border-box;background:0 0;border:0;grid-template-columns:repeat(2,minmax(0,1fr));gap:0;width:100%;min-width:0;padding:0 3px;display:grid;position:relative}.mobile-study-mode-toggle .lesson-mode-switch button{white-space:nowrap;min-width:0;min-height:48px;color:var(--study-muted);background:0 0;border-radius:999px;gap:0;padding:0 4px;font-size:12px;font-weight:500;line-height:1.25}.mobile-study-mode-toggle .lesson-mode-switch button>svg{display:none}.mobile-study-mode-toggle .lesson-mode-switch button[aria-pressed=true]{color:var(--study-primary);box-shadow:none;background:0 0;border-color:#0000;font-weight:650}.mobile-study-mode-toggle .lesson-mode-switch button:hover:not(:disabled){color:var(--study-primary);background:0 0}.mobile-study-mode-toggle .lesson-mode-switch button:focus-visible{outline:2px solid var(--study-primary);outline-offset:-2px}.android-app .learning-page .learning-sticky-controls{border:0}.android-app .learning-page[data-learning-mode] .reading-sheet{padding:16px 16px 28px}.android-app .learning-page[data-learning-mode] .reading-context{margin-bottom:12px;padding-bottom:10px}.android-app .learning-page .content-component:has(>.mobile-block-action){min-height:48px;padding-right:24px;position:relative}.android-app .mobile-block-action{color:#8b7e9a;background:0 0;border:0;border-radius:10px;justify-content:center;align-items:center;width:48px;height:48px;display:inline-flex;position:absolute;top:-9px;right:-12px}.android-app .mobile-block-action:hover{color:#7146b5;background:#f2edf9}.android-app .learning-navigation{background:var(--study-shelf);border-color:var(--study-shelf-line);padding-block:6px;box-shadow:0 -3px 16px #4d3b6714}.android-app .learning-navigation-question{grid-row:2}.android-app .learning-navigation .page-nav{background:var(--study-previous);border:1px solid var(--study-shelf-line);min-height:52px;color:var(--study-nav-ink);border-radius:12px;justify-content:center;gap:6px;padding:8px 10px;box-shadow:0 2px 4px #40206008}.android-app .learning-navigation .page-nav strong,.android-app .learning-navigation .page-nav small{color:var(--study-nav-ink);font-size:13px;font-weight:600;line-height:1.3}.android-app .learning-navigation .page-nav--previous:hover{background:var(--study-previous-hover);border-color:var(--study-nav-hover-line)}.android-app .learning-navigation .page-nav--next:hover{background:var(--study-next-hover);border-color:var(--study-nav-hover-line)}.android-app .learning-navigation .page-nav:focus-visible,.android-app .learning-navigation .teaching-pause--tile:focus-visible{outline:2px solid var(--study-primary);outline-offset:2px}.android-app .learning-navigation .page-nav .page-nav-icon{height:20px;color:var(--study-nav-ink);background:0 0;flex:0 0 16px;display:inline-flex}.android-app .learning-navigation .page-nav .page-nav-icon svg{width:16px;height:16px}.android-app .learning-navigation .page-nav--next,.android-app .learning-navigation .teaching-pause--tile{isolation:isolate;background:var(--study-primary);border:1px solid var(--study-primary);min-width:0;min-height:52px;box-shadow:none;color:var(--study-on-primary);border-radius:12px;gap:5px;padding:8px 10px;position:relative}.android-app .learning-navigation .page-nav--next:before,.android-app .learning-navigation .teaching-pause--tile:before{content:"";z-index:-1;background:var(--study-primary);border-radius:12px;position:absolute;inset:0}.android-app .learning-navigation .page-nav--next:before{background:var(--study-next)}.android-app .learning-navigation .page-nav--next{background:var(--study-next);border-color:var(--study-nav-line)}.android-app .learning-navigation .page-nav--next,.android-app .learning-navigation .page-nav--next small{color:var(--study-nav-ink)}.android-app .learning-navigation .page-nav--next:hover:before{background:var(--study-next-hover)}.android-app .learning-navigation .teaching-pause--tile:hover:not(:disabled),.android-app .learning-navigation .teaching-pause--tile:hover:not(:disabled):before{background:var(--study-primary-hover)}.android-app .learning-navigation .teaching-pause--tile .teaching-pause-copy{font-size:13px;font-weight:600;display:inline}.android-app .learning-navigation .teaching-pause--tile>svg{width:16px;height:16px}.android-app .learning-navigation .teaching-pause--tile:disabled{color:#756b83}.android-app .learning-navigation .teaching-pause--tile:disabled:before{background:#f0edf5}.android-app .learning-navigation-inner,.android-app .learning-navigation--with-doubts .learning-navigation-inner{gap:8px}.android-app .learning-navigation-question .doubt-composer-heading{clip-path:inset(50%);width:1px;height:1px;position:absolute;overflow:hidden}.android-app .learning-navigation--compact-rail,.mobile-settings-dialog,.mobile-revision-dialog,.mobile-selection-dialog,.mobile-image-viewer{--study-shelf:var(--study-toolbar-surface,#eee6f8);--study-shelf-line:var(--study-toolbar-line,#d7c6e9);--study-ink:var(--study-toolbar-ink,#4e316c);--study-muted:#685676;--study-primary:var(--study-toolbar-accent,#7040a6);--study-primary-hover:#60338f;--study-on-primary:#fff;--study-track:#e5d9f1;--study-soft:#f4effa;--study-previous:#f4effa;--study-previous-hover:#e9e0f3;--study-next:#f4effa;--study-next-hover:#e9e0f3;--study-nav-ink:#644282;--study-nav-line:#ded1ec;--study-nav-hover-line:#d7c6e9;--study-icon-surface:#fff}.android-app .learning-page>.learning-navigation--compact-rail{padding:10px 12px calc(8px + env(safe-area-inset-bottom));border:0;border-top:1px solid var(--study-shelf-line);background:var(--study-icon-surface);box-shadow:none;border-radius:0;margin:0 auto}.android-app .learning-navigation--compact-rail .learning-navigation-inner{grid-template-columns:minmax(48px,1fr) auto minmax(48px,1fr);align-items:center;gap:9px 8px;padding:0}.android-app .learning-navigation--compact-rail.learning-navigation--without-playback .learning-navigation-inner{grid-template-columns:repeat(2,minmax(0,1fr))}.android-app .learning-navigation--compact-rail .learning-navigation-question{border-top:1px solid var(--study-nav-line);grid-area:2/1/auto/-1;padding-top:9px}.android-app .learning-navigation--compact-rail[data-keyboard-open] .learning-navigation-inner>:not(.learning-navigation-question){display:none}.android-app .learning-navigation--compact-rail[data-keyboard-open] .learning-navigation-question{border-top:0;grid-row:1;padding-top:0}.android-app .learning-page>.learning-navigation--compact-rail[data-keyboard-open]{padding-top:7px;padding-bottom:7px}.android-app .learning-navigation--compact-rail:has([data-composer-interaction=chat][data-voice-busy]) .learning-navigation-inner>:not(.learning-navigation-question){display:none}.android-app .learning-navigation--compact-rail:has([data-composer-interaction=chat][data-voice-busy]) .learning-navigation-question{border-top:0;grid-row:1;padding-top:0}.android-app .learning-page>.learning-navigation--compact-rail:has([data-composer-interaction=chat][data-voice-busy]){padding-top:7px;padding-bottom:7px}.android-app .learning-navigation--compact-rail .page-nav{border:1px solid var(--lesson-back-border);background:var(--lesson-back-surface);min-height:48px;color:var(--lesson-back-ink);box-shadow:none;text-align:center;border-radius:12px;flex-direction:column;justify-content:center;gap:3px;padding:4px 0}.android-app .learning-navigation--compact-rail .page-nav:before{content:none}.android-app .learning-navigation--compact-rail .page-nav--next .page-nav-icon{order:-1}.android-app .learning-navigation--compact-rail .page-nav strong,.android-app .learning-navigation--compact-rail .page-nav small{overflow-wrap:anywhere;font-size:11px;font-weight:600;line-height:1.4}.android-app .learning-navigation--compact-rail .page-nav:hover{background:var(--lesson-back-hover);border-color:var(--lesson-back-hover-border)}.android-app .learning-navigation--compact-rail .page-nav strong{color:var(--lesson-back-label)}.android-app .learning-navigation--compact-rail .page-nav small{color:#576983}.android-app .learning-navigation--compact-rail .page-nav .page-nav-icon{color:var(--lesson-back-ink)}.android-app .learning-navigation--compact-rail .page-nav--next{background:var(--lesson-next-surface);border-color:var(--lesson-next-border);color:var(--lesson-next-ink)}.android-app .learning-navigation--compact-rail .page-nav--next strong,.android-app .learning-navigation--compact-rail .page-nav--next small{color:var(--lesson-next-label)}.android-app .learning-navigation--compact-rail .page-nav--next .page-nav-icon{color:var(--lesson-next-ink)}.android-app .learning-navigation--compact-rail .page-nav--next:hover{background:var(--lesson-next-hover);border-color:var(--lesson-next-hover-border)}.android-app .mobile-tutor-playback{--lesson-component-surface:#503b62;--lesson-component-border:#705785;--lesson-component-hover:#624778;grid-template-columns:repeat(3,48px);align-items:center;gap:6px;display:grid}.android-app .mobile-tutor-playback .teaching-skip,.android-app .mobile-tutor-playback .teaching-previous{isolation:isolate;width:48px;height:48px;min-height:48px;color:var(--lesson-component-ink);background:var(--lesson-component-surface);border:1px solid var(--lesson-component-border);box-shadow:none;border-radius:12px;gap:0;padding:0;position:static;inset:auto}.android-app .mobile-tutor-playback .teaching-skip:hover:not(:disabled),.android-app .mobile-tutor-playback .teaching-previous:hover:not(:disabled){background:var(--lesson-component-hover)}.android-app .mobile-tutor-playback .teaching-skip:disabled,.android-app .mobile-tutor-playback .teaching-previous:disabled{opacity:.5}.android-app .mobile-tutor-playback .teaching-previous:disabled{opacity:.45}.android-app .mobile-tutor-playback .teaching-skip:focus-visible,.android-app .mobile-tutor-playback .teaching-previous:focus-visible{outline:2px solid var(--study-primary);outline-offset:3px}.android-app .mobile-tutor-playback .teaching-skip svg,.android-app .mobile-tutor-playback .teaching-previous svg{width:20px;height:20px}.android-app .mobile-tutor-playback .teaching-pause--tile{width:48px;min-width:48px;height:48px;min-height:48px;color:var(--lesson-next-ink);background:var(--lesson-next-surface);border:1px solid var(--lesson-next-border);border-radius:50%;padding:0}.android-app .mobile-tutor-playback .teaching-pause--tile:before{content:none}.android-app .mobile-tutor-playback .teaching-pause--tile:hover:not(:disabled){background:var(--lesson-next-hover);border-color:var(--lesson-next-hover-border)}.android-app .mobile-tutor-playback .teaching-pause--tile[data-paused=true]:not(:disabled){color:var(--lesson-resume-ink);background:var(--lesson-resume-surface);border-color:var(--lesson-resume-border)}.android-app .mobile-tutor-playback .teaching-pause--tile[data-paused=true]:hover:not(:disabled){background:var(--lesson-resume-hover);border-color:var(--lesson-resume-hover-border)}.android-app .mobile-tutor-playback .teaching-pause--tile:disabled{color:var(--lesson-playback-disabled-ink);background:var(--lesson-playback-disabled-surface);border-color:var(--lesson-playback-disabled-border)}.android-app .mobile-tutor-playback .teaching-pause--tile .teaching-pause-copy{display:none}.android-app .mobile-tutor-playback .teaching-pause--tile>svg{width:20px;height:20px}.mobile-settings-dialog.shared-dialog,.mobile-revision-dialog.shared-dialog,.mobile-selection-dialog.shared-dialog{border:1px solid var(--study-shelf-line);background:var(--study-icon-surface);color:var(--study-ink);border-radius:18px;padding:0;box-shadow:0 8px 32px #3a23502a}.mobile-settings-dialog.shared-dialog{inset:var(--lesson-settings-top,60px) var(--lesson-settings-right,12px) auto auto;width:min(360px,100vw - 24px);max-height:calc(var(--native-viewport-height,100dvh) - var(--lesson-settings-top,60px) - 12px - env(safe-area-inset-bottom));border-radius:16px;margin:0;position:fixed}.mobile-settings-dialog::backdrop{background:#30243d38}.mobile-settings-dialog .dialog-heading,.mobile-revision-dialog .dialog-heading,.mobile-selection-dialog .dialog-heading{border-bottom:1px solid var(--study-shelf-line);background:var(--study-soft);gap:8px;padding:10px 16px}.mobile-settings-dialog .dialog-heading h2,.mobile-revision-dialog .dialog-heading h2,.mobile-selection-dialog .dialog-heading h2{letter-spacing:-.025em;font-size:16px}.mobile-settings-dialog .dialog-heading button,.mobile-revision-dialog .dialog-heading button,.mobile-selection-dialog .dialog-heading button{min-width:48px;min-height:48px;padding:0 6px;font-size:12px}.mobile-settings-dialog .dialog-body{padding:4px 20px 20px}.mobile-setting-section+.mobile-setting-section{border-top:1px solid #eee8f5}.mobile-setting-row{text-align:left;width:100%;min-height:54px;font:inherit;background:0 0;border:0;align-items:center;gap:8px;padding:0;font-size:13px;display:flex}.mobile-setting-row span:nth-child(2){color:var(--study-muted);margin-left:auto;font-size:12px}.mobile-setting-row[aria-expanded=true]>svg{transform:rotate(180deg)}.mobile-setting-options:not([hidden]){grid-template-columns:repeat(2,minmax(0,1fr));gap:8px;padding-bottom:12px;display:grid}.mobile-setting-options button{border:1px solid var(--study-nav-line);background:var(--study-icon-surface);min-height:48px;color:var(--study-ink);font:inherit;border-radius:10px;justify-content:center;align-items:center;gap:6px;padding:8px;font-size:13px;display:flex}.mobile-setting-options button[aria-pressed=true]{background:var(--study-shelf);border-color:var(--study-primary);color:var(--study-ink)}.mobile-setting-options button:disabled{opacity:.5}.mobile-setting-options--voice button{flex-direction:column;min-height:106px;padding:12px;font-weight:600;position:relative}.mobile-setting-options--voice button>svg:last-child:not(.mobile-voice-avatar){position:absolute;top:8px;right:8px}.mobile-voice-avatar{flex-shrink:0;width:48px;height:48px}.mobile-setting-options--speed:not([hidden]){display:block}.mobile-settings-dialog .playback-speed-value{color:var(--study-ink);margin:0 0 12px;font-size:30px}.mobile-settings-dialog .playback-speed-adjuster{gap:12px}.mobile-settings-dialog .playback-speed-adjuster button{background:var(--study-soft);flex:0 0 48px;width:48px;min-height:48px}.mobile-settings-dialog .playback-speed-adjuster input{background:0 0;width:100%;min-width:0;height:48px;margin:0}.mobile-settings-dialog .playback-speed-adjuster input::-webkit-slider-runnable-track{background:linear-gradient(to right, var(--study-primary) var(--speed-fill), var(--study-track) var(--speed-fill));border-radius:6px;height:6px}.mobile-settings-dialog .playback-speed-adjuster input::-webkit-slider-thumb{margin-top:-6px}.mobile-settings-dialog .playback-speed-adjuster input::-moz-range-track{background:linear-gradient(to right, var(--study-primary) var(--speed-fill), var(--study-track) var(--speed-fill));border-radius:6px;height:6px}.mobile-settings-dialog .playback-speed-presets{grid-template-columns:repeat(3,minmax(0,1fr));gap:6px;margin-top:14px;display:grid}.mobile-settings-dialog .playback-speed-presets button{min-width:0;min-height:48px}.mobile-settings-note{color:var(--study-muted);font-size:12px}.mobile-revision-dialog.shared-dialog{width:min(496px,100vw - 24px);max-height:none;height:calc(var(--native-viewport-height,100dvh) - 78px);margin:0 auto;position:fixed;inset:60px 12px 18px}.mobile-revision-dialog .dialog-heading{flex-direction:row}.mobile-revision-dialog .eyebrow{letter-spacing:0;text-transform:none;margin:0 0 3px;font-size:11px}.mobile-revision-dialog .dialog-body{padding:14px 16px;overflow-y:auto}.mobile-revision-dialog .revision-feed,.android-app .mobile-course-collection .revision-feed{gap:0}.mobile-revision-dialog .revision-item,.android-app .mobile-course-collection .revision-item{background:#fff;border:0;border-bottom:1px solid #eee8f5;border-radius:0;padding:0;position:relative}.mobile-revision-summary{min-height:76px;padding:14px 76px 14px 0;list-style:none;position:relative}.mobile-revision-summary::-webkit-details-marker{display:none}.mobile-revision-summary>svg{color:#897698;position:absolute;top:34px;right:54px}.mobile-revision-dialog .mobile-revision-summary h4,.android-app .mobile-course-collection .mobile-revision-summary h4{margin:4px 0;font-size:14px;font-weight:600;line-height:1.4}.mobile-revision-dialog .mobile-revision-excerpt,.android-app .mobile-course-collection .mobile-revision-excerpt{color:#77648e;-webkit-line-clamp:2;-webkit-box-orient:vertical;margin:0;font-size:12px;display:-webkit-box;overflow:hidden}details[open]>.mobile-revision-summary>svg{transform:rotate(180deg)}.mobile-revision-detail{padding:0 0 16px}.mobile-revision-detail .revision-source-preview{background:0 0;border:0;margin-top:0;padding:0}.mobile-revision-detail .revision-item-actions a{align-items:center;min-height:48px;display:inline-flex}.mobile-revision-detail .revision-item-actions button{min-width:48px;min-height:48px}.mobile-revision-remove{z-index:1;color:#a55368;background:#fff1f4;border:0;border-radius:10px;place-items:center;width:48px;height:48px;display:grid;position:absolute;top:10px;right:0}.mobile-revision-remove:disabled{opacity:.5}.mobile-revision-remove:focus-visible{outline-offset:2px;outline:2px solid #a55368}.mobile-selection-dialog.shared-dialog{width:min(496px,100vw - 24px);max-height:calc(var(--native-viewport-height,100dvh) * .72);margin:0 auto;position:fixed;inset:auto 12px 14px}.mobile-selection-dialog .dialog-body{padding:12px 16px}.mobile-image-viewer.shared-dialog{width:100%;max-width:none;height:var(--native-viewport-height,100dvh);background:var(--study-icon-surface);max-height:none;color:var(--study-ink);border:0;border-radius:0;margin:0;padding:0;position:fixed;inset:0;overflow:hidden}.mobile-image-viewer[open]{flex-direction:column;display:flex}.mobile-image-viewer .dialog-heading{border-bottom:1px solid var(--study-shelf-line);background:var(--study-soft);flex:none;gap:12px;padding:6px 12px}.mobile-image-viewer .dialog-heading>div{min-width:0}.mobile-image-viewer .dialog-heading h2{white-space:nowrap;text-overflow:ellipsis;font-size:16px;overflow:hidden}.mobile-image-viewer .dialog-heading button{min-width:48px;min-height:48px;color:var(--study-ink);flex-shrink:0;padding:0 8px;font-size:14px}.mobile-image-viewer .dialog-body{flex:1 1 0;grid-template-rows:minmax(0,1fr) auto;min-height:0;max-height:none;padding:0;display:grid;overflow:hidden}.mobile-image-viewer-canvas{touch-action:none;-webkit-user-select:none;user-select:none;place-items:center;min-height:0;padding:12px;display:grid;overflow:hidden}.mobile-image-viewer-canvas[data-zoomed]{cursor:grab}.mobile-image-viewer-canvas:focus-visible{outline:2px solid var(--study-primary);outline-offset:-2px}.mobile-image-viewer-canvas picture{width:100%;height:100%;min-height:0}.mobile-image-viewer-canvas img{object-fit:contain;transform-origin:50%;pointer-events:none;width:100%;height:100%;min-height:0;display:block}.mobile-image-viewer-actions{padding:10px 12px calc(10px + env(safe-area-inset-bottom));border-top:1px solid var(--study-shelf-line);background:var(--study-icon-surface);grid-template-columns:repeat(2,minmax(0,1fr));gap:8px;display:grid}.mobile-image-viewer-actions>button{justify-content:center;min-width:0;min-height:48px;margin:0;padding:8px;font-size:14px;line-height:1.3}.mobile-selection-actions{flex-direction:column;gap:4px;display:flex}.mobile-selection-actions>button{width:100%;min-height:48px;box-shadow:none;border:0;justify-content:flex-start;font-size:13px}.mobile-selection-preview{max-height:calc(var(--native-viewport-height,100dvh) * .24);border-bottom:1px solid #eee8f5;margin-bottom:8px;padding:0 0 12px;overflow-y:auto}.mobile-selection-preview .leaf{font-size:15px}@media (max-width:390px){.mobile-study-ai .mobile-study-ai-label{display:none}.mobile-study-ai .mobile-study-ai-label-short{display:inline}}@media (max-width:360px){.android-app .doubt-conversation,.android-app .learning-page[data-learning-mode] .reading-sheet{padding-inline:12px}.app-shell:has(.mobile-study-controls) .header-inner{padding-inline:6px}.mobile-study-mode-toggle{width:124px}}@media (max-width:340px){.mobile-study-controls{gap:0}.mobile-study-mode-toggle{width:116px}.mobile-study-ai{padding-inline:0}}@media (prefers-reduced-motion:reduce){.android-app *{scroll-behavior:auto!important}.mobile-study-mode-toggle:after{transition:none}}.android-app .mobile-formula{grid-template-columns:minmax(0,1fr) 48px;align-items:start;gap:4px;width:100%;min-width:0;max-width:100%;display:grid}.android-app .mobile-formula-scroll{scrollbar-width:thin;scrollbar-color:#b6a3c9 #f6f2fa;min-width:0;padding:12px 6px;overflow-x:auto}.android-app .mobile-formula-scroll>.math-expression,.mobile-formula-expanded .math-expression{white-space:nowrap;min-width:max-content;display:inline-block}.android-app .mobile-formula .katex,.mobile-formula-expanded .katex{font-size:var(--study-math-scale,1.2em);white-space:nowrap}.android-app .mobile-formula-scroll{font-size:max(16px,1em)}.android-app .formula-leaf[data-teaching-current=true] .mobile-formula-scroll>.math-expression{background:var(--spoken-text-surface,#f3edf9);border-radius:2px}.android-app .mobile-formula-expand,.mobile-formula-tools button{color:#7040a6;cursor:pointer;background:#faf8fc;border:1px solid #e2dbea;border-radius:8px;justify-content:center;align-items:center;min-width:48px;min-height:48px;display:inline-flex}.android-app .mobile-formula-expand:focus-visible,.android-app .mobile-formula-scroll:focus-visible,.mobile-formula-tools button:focus-visible,.mobile-formula-expanded:focus-visible{outline-offset:2px;outline:2px solid #7040a6}.mobile-formula-dialog.shared-dialog{width:calc(100% - 24px);max-width:720px;max-height:calc(var(--native-viewport-height,100dvh) - 24px);color:#402060;background:#fff;border:1px solid #e2dbea;border-radius:14px;margin:auto;padding:0;position:fixed;inset:12px}.mobile-formula-dialog .dialog-heading{background:#f3edf9;border-bottom:1px solid #e2dbea;padding:12px 16px}.mobile-formula-dialog .dialog-body{padding:16px}.mobile-formula-tools{align-items:center;gap:8px;display:flex}.mobile-formula-tools output{text-align:center;font-variant-numeric:tabular-nums;min-width:48px}.mobile-formula-tools button:disabled{opacity:.45;cursor:default}.mobile-formula-hint{color:#685676;margin-block:12px;font-size:13px}.mobile-formula-expanded{max-height:clamp(160px, calc(var(--native-viewport-height,100dvh) * .55), 560px);padding:24px 8px;font-size:20px;overflow:auto}
:is(.app-shell:has([data-tutor-controls=compact]),[data-tutor-controls=compact]){--study-shelf:var(--study-toolbar-surface,#eee6f8);--study-shelf-line:var(--study-toolbar-line,#d7c6e9);--study-ink:var(--study-toolbar-ink,#4e316c);--study-muted:#685676;--study-primary:var(--study-toolbar-accent,#7040a6);--study-primary-hover:#60338f;--study-track:var(--study-toolbar-surface,#eee6f8);--study-icon-surface:#fff;--study-soft:#f4effa;--study-save-surface:#fff;--study-save-hover:#f4effa;--study-save-ink:var(--study-toolbar-ink,#4e316c)}.app-shell:has([data-tutor-controls=compact]) .mobile-study-mode-toggle{align-items:center;width:132px;display:flex}.app-shell:has([data-tutor-controls=compact]) .mobile-study-mode-toggle:before{content:none}.app-shell:has([data-tutor-controls=compact]) .mobile-study-mode-toggle:after{content:none}.app-shell:has([data-tutor-controls=compact]) .mobile-study-mode-toggle .lesson-mode-switch{white-space:nowrap;background:#e5d9f1;border:1px solid #0000;border-radius:9px;gap:2px;padding:2px}.app-shell:has([data-tutor-controls=compact]) .mobile-study-mode-toggle .lesson-mode-switch button{min-height:26px;color:var(--study-toolbar-ink,#4e316c);border-radius:9px;gap:4px;padding:3px;font-size:12px;font-weight:500;position:relative}.app-shell:has([data-tutor-controls=compact]) .mobile-study-mode-toggle .lesson-mode-switch button:after{content:"";inset-inline:0;height:48px;position:absolute;top:50%;transform:translateY(-50%)}.app-shell:has([data-tutor-controls=compact]) .mobile-study-mode-toggle .lesson-mode-switch button>svg{flex-shrink:0;width:14px;height:14px;display:block}.app-shell:has([data-tutor-controls=compact]) .mobile-study-mode-toggle .lesson-mode-switch button[aria-pressed=true]{background:var(--study-toolbar-accent,#7040a6);color:#fff;box-shadow:none;border-color:#0000}.app-shell:has([data-tutor-controls=compact]) .mobile-study-mode-toggle .lesson-mode-switch button:hover:not(:disabled):not([aria-pressed=true]){background:#f8f4fc}.app-shell:has([data-tutor-controls=compact]) .mobile-study-icon{width:40px}.app-shell:has([data-tutor-controls=compact]) .mobile-study-save.mobile-study-icon:before{border-color:var(--study-toolbar-line,#d7c6e9)}.app-shell:has([data-tutor-controls=compact]) .mobile-study-ai{flex:0 auto;width:auto;min-width:48px;position:absolute;left:50%;transform:translate(-50%)}.app-shell:has([data-tutor-controls=compact]) .mobile-study-controls{gap:8px;position:relative}.app-shell:has([data-tutor-controls=compact]) .mobile-study-controls .mobile-study-save{margin-left:auto}.app-shell:has([data-tutor-controls=compact]) .header-inner{padding-inline:6px}@media not (min-width:480px){.app-shell:has([data-tutor-controls=compact]) .mobile-study-controls{gap:4px}.app-shell:has([data-tutor-controls=compact]) .mobile-study-ai{position:relative;left:auto;transform:none}}@media not (min-width:380px){.app-shell:has([data-tutor-controls=compact]) .mobile-study-controls{gap:2px}.app-shell:has([data-tutor-controls=compact]) .mobile-study-mode-toggle{width:124px}.app-shell:has([data-tutor-controls=compact]) .mobile-study-mode-toggle .lesson-mode-switch button{gap:4px;padding-inline:3px;font-size:12px}.app-shell:has([data-tutor-controls=compact]) .mobile-study-mode-toggle .lesson-mode-switch button>svg{width:14px;height:14px}.app-shell:has([data-tutor-controls=compact]) .mobile-study-icon{width:36px}.app-shell:has([data-tutor-controls=compact]) .header-inner{padding-inline:4px}}@media (forced-colors:active){.app-shell:has([data-tutor-controls=compact]) .lesson-mode-switch button[aria-pressed=true]{outline-offset:-3px;outline:2px solid highlight}}
.BrowserTutorFrame-module__qf1EoW__wide{display:contents}.BrowserTutorFrame-module__qf1EoW__compact{--browser-tutor-width:100%;width:100%;height:100%;min-height:0;container-type:inline-size}.app-shell:has(.BrowserTutorFrame-module__qf1EoW__compact)>#main-content>.BrowserTutorFrame-module__qf1EoW__compact.BrowserTutorFrame-module__qf1EoW__compact{max-width:var(--browser-tutor-width)}.app-shell:has(.BrowserTutorFrame-module__qf1EoW__compact) .header-inner{max-width:var(--browser-tutor-width,100%);padding-inline:max(6px, env(safe-area-inset-left)) max(6px, env(safe-area-inset-right));gap:0}:is(.app-shell:has(.BrowserTutorFrame-module__qf1EoW__compact) .page-header-study-mode,.app-shell:has(.BrowserTutorFrame-module__qf1EoW__compact) .header-default-actions){display:none}.BrowserTutorFrame-module__qf1EoW__compact .learning-page{padding-inline:max(10px, env(safe-area-inset-left)) max(10px, env(safe-area-inset-right))}.BrowserTutorFrame-module__qf1EoW__compact .doubt-panel[data-layout=compact]{width:min(100%,780px)}:is(.BrowserTutorFrame-module__qf1EoW__compact .mobile-image-viewer,.BrowserTutorFrame-module__qf1EoW__compact .chapter-dialog,.BrowserTutorFrame-module__qf1EoW__compact .mobile-revision-dialog){max-height:calc(var(--native-viewport-height,100dvh) - 24px)}@media (768px<=width<1024px){.BrowserTutorFrame-module__qf1EoW__compact{--browser-tutor-width:780px;max-width:var(--browser-tutor-width)}.app-shell:has(.BrowserTutorFrame-module__qf1EoW__compact) .header-inner{max-width:780px;padding-inline:16px}.BrowserTutorFrame-module__qf1EoW__compact .learning-page[data-learning-mode] .reading-sheet{padding:24px 32px 32px}.BrowserTutorFrame-module__qf1EoW__compact .learning-page .lesson-title{font-size:1.875rem}}@container (min-width:600px){.BrowserTutorFrame-module__qf1EoW__compact .learning-navigation--compact-rail .learning-navigation-inner{column-gap:16px}}
.LessonFonts-module__mUj_0a__options{min-width:0;display:grid}.LessonFonts-module__mUj_0a__options button{border:0;border-bottom:1px solid var(--study-shelf-line,#e4dbee);width:100%;min-height:3rem;color:var(--study-ink,#3a2d49);text-align:start;overflow-wrap:anywhere;background:0 0;border-radius:0;justify-content:space-between;align-items:center;gap:.5rem;padding:.75rem;font-size:1.125rem;line-height:1.4;display:flex}.LessonFonts-module__mUj_0a__options button:last-child{border-bottom:0}.LessonFonts-module__mUj_0a__options button[aria-pressed=true]{background:var(--study-shelf,#eee5f7);color:var(--study-primary,#7040a6)}.LessonFonts-module__mUj_0a__options button:hover{background:var(--study-soft,#f5f0fa)}.LessonFonts-module__mUj_0a__options svg{flex-shrink:0}.LessonFonts-module__mUj_0a__options button:focus-visible,.LessonFonts-module__mUj_0a__footer button:focus-visible{outline:2px solid var(--study-primary,#7040a6);outline-offset:-2px}.LessonFonts-module__mUj_0a__sizes{margin-block:.25rem .75rem}.LessonFonts-module__mUj_0a__segmented{border:1px solid var(--study-shelf-line,#e4dbee);border-radius:.5rem;flex-wrap:wrap;display:flex;overflow:hidden}.LessonFonts-module__mUj_0a__segmented button{width:auto;font:inherit;border:0;flex:4rem;justify-content:center;padding:.5rem;font-size:.8125rem}.LessonFonts-module__mUj_0a__footer{border-top:1px solid var(--study-shelf-line,#e4dbee);flex-wrap:wrap;justify-content:space-between;align-items:center;gap:.5rem;margin-top:.75rem;padding-top:.75rem;display:flex}.LessonFonts-module__mUj_0a__targets{flex-wrap:wrap;gap:.25rem;display:flex}.LessonFonts-module__mUj_0a__targets button{min-width:3rem;min-height:3rem;color:var(--study-muted,#6e5d7c);font:inherit;background:0 0;border:0;padding:.5rem .75rem;font-size:.875rem;font-weight:600;position:relative}.LessonFonts-module__mUj_0a__targets button[aria-pressed=true]{color:var(--study-primary,#7040a6)}.LessonFonts-module__mUj_0a__targets button[aria-pressed=true]:after{content:"";bottom:.125rem;background:currentColor;border-radius:3px;height:3px;position:absolute;inset-inline:30%}.LessonFonts-module__mUj_0a__done{background:var(--study-shelf,#eee5f7);min-height:3rem;color:var(--study-primary,#7040a6);font:inherit;border:0;border-radius:2rem;margin-left:auto;padding:.5rem 1.125rem;font-size:.875rem;font-weight:600}.LessonFonts-module__mUj_0a__control{position:relative}.LessonFonts-module__mUj_0a__syncStatus{color:var(--study-muted,#6e5d7c);font-size:.8125rem;line-height:1.5}.LessonFonts-module__mUj_0a__syncStatus button{color:var(--study-primary,#7040a6);font:inherit;background:0 0;border:0;padding:.5rem;text-decoration:underline}.LessonFonts-module__mUj_0a__trigger{border:1px solid var(--study-shelf-line,#e4dbee);background:var(--study-icon-surface,#fff);min-height:2.5rem;color:var(--study-primary,#7040a6);font:inherit;border-radius:.625rem;padding:.5rem .875rem;font-size:.875rem;font-weight:600}.LessonFonts-module__mUj_0a__panel{inset:var(--font-menu-top,4rem) var(--font-menu-right,1rem) auto auto;width:min(23rem,100vw - 1.5rem);max-height:calc(100dvh - var(--font-menu-top,4rem) - .75rem);border:1px solid var(--study-shelf-line,#e4dbee);background:var(--study-icon-surface,#fff);color:var(--study-ink,#3a2d49);z-index:100;border-radius:.75rem;margin:0;padding:1rem;display:none;position:fixed;overflow-y:auto;box-shadow:0 8px 24px #30243d25}:is(.LessonFonts-module__mUj_0a__panel:popover-open,.LessonFonts-module__mUj_0a__panel[data-fallback-open=true]){display:block}.LessonFonts-module__mUj_0a__heading{margin:0 0 .5rem;font-size:.875rem;font-weight:600}.LessonFonts-module__mUj_0a__sizeHeading{margin:1rem 0 .5rem;font-size:.875rem;font-weight:600}