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@media(prefers-reduced-motion:reduce){*,*:before,*:after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}
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@media(max-width:760px){.mode-tabs{gap:0 18px;flex-wrap:wrap}.mode-tabs .later{flex-basis:100%;margin-left:0;padding:0 0 8px;font-size:10px}}
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/* Teaching timelines: drawings explain transformations, with no autoplay. */
.canvas-lesson canvas{display:block;width:100%;aspect-ratio:640/300;height:auto}
.canvas-narration{font-size:13px;line-height:1.6;min-height:42px;margin:8px 0 12px;color:var(--ink,#17334b)}
.canvas-transport{display:flex;align-items:center;gap:8px;flex-wrap:wrap}
.canvas-transport label{flex:1 1 180px;font-size:11px;line-height:1.6}
.canvas-transport input{display:block;width:100%;accent-color:#1557c7;min-height:28px}
.canvas-transport output{font-size:12px;min-width:36px;font-variant-numeric:tabular-nums}
.canvas-help{font-size:10px;color:#586e81;margin:9px 0}
@media(max-width:500px){.canvas-narration{min-height:62px}.canvas-transport label{flex-basis:100%;order:3}.canvas-transport .button{min-height:40px}.canvas-lesson canvas{min-width:0}}
@media print{.canvas-transport,.canvas-help{display:none}}
.controls .button.primary{background:var(--blue);color:#fff}
.controls .button.primary:hover:not(:disabled){background:#1049ae}

/* Maths uses the Physics topic workspace and connected study-map vocabulary. */
.site-header{height:58px;border-bottom:1px solid #e4ebf5;background:#fff}
.header-inner{max-width:none;padding:0 30px}
.physics-brand{font:800 17px/1.3 'Outfit','Segoe UI',sans-serif;text-transform:uppercase;letter-spacing:-.5px}
.course-header-label{font-size:11px;color:#5a7396}
.guest-label{display:flex;align-items:center;gap:9px;font-size:12px;color:#5a7396}
.guest-avatar{display:grid;place-items:center;background:#edf3fb;color:#285caf;border:1px solid #d6e1ee;border-radius:50%;width:29px;height:29px;font-size:10px}
.topic-workspace{display:grid;grid-template-columns:235px minmax(0,1fr);max-width:1600px;margin:auto;min-height:calc(100vh - 58px);background:#fff}
.course-directory{background:#f8fafd;border-right:1px solid #e4ebf5;padding:24px 18px;align-self:stretch}
.course-return{font-size:12px;display:block;margin-bottom:25px}
.directory-course{font-weight:700;font-size:15px;color:#0b2545}.directory-course small{display:block;font-size:11px;font-weight:400;color:#5a7396;margin-top:5px}
.directory-label{font-size:10px;letter-spacing:1.5px;color:#5a7396;margin:30px 0 12px}
.directory-topic{display:flex;gap:12px;padding:12px 10px;font-size:12px;line-height:1.5;color:#5a7396;border-radius:6px;margin-bottom:5px}
.directory-topic>span{font-size:11px;min-width:18px}.directory-topic.active{background:#e1edfd;color:#0a2f73;border-left:3px solid #285caf}
.directory-topic small{display:block;font-size:10px;color:#7a8b9d;margin-top:3px}.directory-hint{font-size:11px;color:#5a7396;line-height:1.8;border-top:1px solid #dfe7f0;padding-top:16px;margin-top:30px}
.overview{width:100%;max-width:1240px;padding:22px 28px 40px;background:#fff}
.topic-toolbar{display:flex;align-items:center;justify-content:space-between;gap:10px;margin-bottom:22px}.topic-toolbar .breadcrumb{margin:0}.breadcrumb>span{padding:0 8px;color:#91a2b5}
.overview-head{margin-bottom:22px;align-items:center}.overview-head h1{font:600 29px/1.25 'Outfit','Segoe UI',sans-serif;letter-spacing:-.7px;color:#0b2545}.overview-head .eyebrow{display:inline-block;background:#edf3fb;padding:4px 9px;color:#3d5a80;border-radius:4px;font-size:10px;letter-spacing:.3px;margin-bottom:10px}.overview-head .intro-text{font-size:13px;margin:0}.overview-meta{flex-direction:column;align-items:flex-end;gap:5px;flex-shrink:0}
.maths-study-map{background:#fff;border:1px solid #dce5ef;border-radius:7px;padding:16px}
.maths-study-map .map-heading{margin:0 0 14px}.maths-study-map .map-heading h2{font-size:18px;margin:0 0 4px;color:#0b2545}.maths-study-map .map-heading p{font-size:13px;color:#5a7396;margin:0}
.maths-study-map .map-sheet{border:0}.maths-study-map .map-canvas{height:560px;min-width:1100px}.maths-study-map .map-lines{height:550px}.maths-study-map .map-lines path{stroke-width:3;fill:none;stroke-linecap:round}.maths-study-map .map-lines text{font-size:13px;font-weight:600;fill:#344f69}
.maths-study-map .map-node{width:23%;height:138px;padding:9px 12px;border:3px solid var(--c);border-radius:6px 13px 7px 9px;background:var(--wash);color:#17334b;transition:transform 160ms cubic-bezier(.23,1,.32,1),background-color 150ms ease,border-color 150ms ease;transform-origin:center}
.maths-study-map .map-node[data-unit="1-1"],.maths-study-map .map-node[data-unit="1-2"]{top:208px}.maths-study-map .map-node[data-unit="1-3"],.maths-study-map .map-node[data-unit="1-4"]{top:8px}
.maths-study-map .map-node .node-top{font-size:10px;margin-bottom:4px;color:var(--c)}.maths-study-map .map-status{font-size:9px;letter-spacing:.1px}.maths-study-map .map-node .node-symbol{font-size:17px;color:var(--c)}
.maths-study-map .map-node h2{font-size:15px;line-height:1.3;white-space:normal;font-weight:650;margin:0 0 6px;letter-spacing:-.2px}.maths-study-map .map-node p.node-formula{font:16px/1.35 Georgia,serif;color:var(--c);margin:0 0 5px;white-space:nowrap}.maths-study-map .map-node p.node-cue{font:12px/1.35 'Segoe Print','Bradley Hand',cursive;color:var(--c);margin:0}
.maths-study-map .map-hub{border:3px solid #5474a4;background:#e6effc;top:219px;height:104px}.maths-study-map .map-hub strong{font:650 24px/1.4 'Outfit','Segoe UI',sans-serif;color:#284e8b}.maths-study-map .map-hub em{font:11px/1.5 'Segoe Print',cursive;color:#886a32;margin-top:6px}.maths-study-map .map-footer{padding:12px 0 0;border-color:#e4ebf5;color:#5a7396}.mobile-map-hint{display:none}
.maths-study-map .map-node:focus-visible{z-index:5;outline:3px solid var(--c);outline-offset:4px}.maths-study-map .map-node:focus-visible h2{text-decoration:underline;text-underline-offset:3px}
@media(hover:hover) and (pointer:fine){.maths-study-map .map-node:hover{z-index:5;transform:scale(1.035);background:color-mix(in srgb,var(--wash) 65%,white);border-color:var(--c)}.maths-study-map .map-node:hover h2{text-decoration:underline;text-underline-offset:3px}.maths-study-map .map-node:active{transform:scale(.985)}}
.topic-outcomes{display:grid;grid-template-columns:minmax(0,1.8fr) minmax(0,1fr);gap:28px;margin-top:24px;padding:23px 0 5px;border-top:2px solid #dce5ef}.topic-outcomes .eyebrow{font-size:10px;letter-spacing:1.2px;color:#5a7396;margin-bottom:9px}.topic-outcomes h2{font-size:21px;margin:0 0 9px}.outcomes-intro{font-size:12px;color:#647487;line-height:1.65}.topic-outcomes ul{padding-left:19px;margin:0}.topic-outcomes li{font-size:13px;line-height:1.75;margin-bottom:10px}.topic-outcomes li strong{font-weight:650}.topic-outcomes li small{color:#607b9c;font-size:10px;white-space:nowrap}.tier-note{font-size:11px;color:#6f6184;line-height:1.7;margin-top:12px}.outcomes-use{border-left:3px solid #77a88e;background:#eef6f0;padding:18px;align-self:start;border-radius:0 7px 7px 0}.outcomes-use h3{font:500 21px/1.3 Georgia,serif;margin-bottom:14px}.outcomes-use a{font-size:11px}.outcomes-use li{font-size:12px}
@media(max-width:1100px){.topic-workspace{grid-template-columns:190px minmax(0,1fr)}.course-directory{padding:22px 12px}.overview{padding:20px}.overview-head{align-items:flex-start;flex-direction:column}.overview-meta{flex-direction:row;align-items:center}}
@media(max-width:760px){.header-inner{padding:0 16px}.course-header-label,.guest-label{display:none}.topic-workspace{display:block}.course-directory{display:none}.overview{padding:17px 13px 30px}.topic-toolbar{margin-bottom:20px}.topic-toolbar .preview-tag{display:none}.topic-toolbar .breadcrumb{font-size:10px}.overview-head h1{font-size:26px}.maths-study-map{padding:12px}.topic-outcomes{grid-template-columns:1fr;gap:16px;margin-top:20px;padding-top:20px}.mobile-map-hint{display:inline}.topic-outcomes li{font-size:13px}.overview-meta{flex-wrap:wrap}}
@media(prefers-reduced-motion:reduce){.maths-study-map .map-node:hover{transform:none}}
html[data-reduced="true"] .maths-study-map .map-node:hover{transform:none}
.maths-study-map .map-lines path:nth-of-type(1){stroke:#3867ad}.maths-study-map .map-lines path:nth-of-type(2){stroke:#408970}.maths-study-map .map-lines path:nth-of-type(3){stroke:#428691}.maths-study-map .map-lines path:nth-of-type(4){stroke:#b47a45}.maths-study-map .map-lines path:nth-of-type(5){stroke:#9474a9}.maths-study-map .map-lines path:nth-of-type(6){stroke:#bb7374}.maths-study-map .map-lines path:nth-of-type(7){stroke:#6675ac}

/* Shared Physics-style chapter navigation in topic and lesson views. */
.topic-workspace,.workspace{--directory-width:300px;display:grid;grid-template-columns:var(--directory-width) minmax(0,1fr);gap:0;max-width:1600px;width:100%;margin:auto;padding:0;background:#fff;min-height:calc(100vh - 58px)}
.topic-workspace.directory-collapsed,.workspace.directory-collapsed{--directory-width:30px}
.course-directory{position:sticky;top:0;align-self:start;height:calc(100vh - 58px);padding:0;background:#fff;border-right:1px solid #e4ebf5;z-index:20;min-width:0;font:14px/1.5 'Inter',system-ui,-apple-system,sans-serif;color:#5a7396}
.directory-inner{height:100%;overflow-y:auto;padding:23px 18px 30px;scrollbar-width:thin}
.directory-collapsed .directory-inner{display:none}
.sidebar-collapse-circle{position:absolute;right:-14px;top:24px;width:28px;height:28px;border:1px solid #c7d7ec;border-radius:50%;background:white;color:#42597a;display:grid;place-items:center;font-size:11px;padding:0;z-index:2}
.sidebar-collapse-circle:hover{background:#e8f1fe;border-color:#7c93b4}
.chapter-toggle{font:12px/1.4 'Inter',system-ui,sans-serif;min-height:34px;padding:6px 11px;color:#42597a}
.course-directory .directory-topic{display:flex;justify-content:space-between;gap:10px;border:0;border-radius:6px;padding:8px 12px;margin:0;color:#0b2545;list-style:none;cursor:pointer;line-height:1.5}
.directory-topic::-webkit-details-marker{display:none}.minimal-topic-title{font-size:15.2px;font-weight:800;min-width:0}.minimal-topic-chevron{font-size:11px;color:#5a7396;flex-shrink:0;padding-top:4px}
.minimal-topic-container{margin-bottom:4px}.minimal-topic-container[open]>.directory-topic{background:#f3f7fd}.minimal-topic-container[open] .minimal-topic-chevron{transform:rotate(90deg)}
.course-directory .directory-topic.active{background:#e8f1fe;color:#0b2545}.directory-topic:hover{background:#f3f7fd}
.minimal-subtopics-list{margin:4px 0 12px 20px;padding-left:12px;border-left:1px solid #e4ebf5;display:flex;flex-direction:column;gap:2px}
.minimal-subtopic-item{display:flex;align-items:center;gap:10px;border:0;border-radius:6px;background:transparent;padding:6px 8px;line-height:1.5;color:#5a7396;text-align:left;text-decoration:none;width:100%;font:13px/1.5 'Inter',system-ui,-apple-system,sans-serif}
.minimal-subtopic-item:hover{background:#e8f1fe;color:#0b2545}.minimal-subtopic-item.current{background:#cfe0fa;color:#0a2f73;font-weight:800;text-decoration:underline;text-underline-offset:2px}.minimal-subtopic-item small{display:block;font-size:10px;font-weight:400;color:#7b8da4;margin-top:3px}.minimal-subtopic-indicator{font-size:12px;flex:0 0 14px;text-align:center}
.chapter-overview-link{font-size:12px;color:#1557c7;padding:6px 8px;margin-bottom:4px}.course-directory summary:focus-visible{outline:3px solid #83a9e8;outline-offset:2px}
.lesson-body{width:100%;max-width:1240px;margin:0 auto;padding:28px 35px 45px;min-width:0}.directory-backdrop{display:none}
@media(max-width:760px){
 .course-directory{display:block;position:fixed;top:58px;left:0;width:min(320px,85vw);height:calc(100dvh - 58px);z-index:50;background:white}
 .topic-workspace,.workspace{display:block}.directory-collapsed .course-directory{display:none}.sidebar-collapse-circle{right:10px;top:15px}.directory-inner{padding:22px 16px}.course-return{padding-right:25px}
 .directory-backdrop{display:block;position:fixed;inset:58px 0 0;background:#0b254530;border:0;z-index:40;width:100%;height:calc(100dvh - 58px)}.directory-collapsed .directory-backdrop{display:none}
 .lesson-body{padding:20px 15px 35px}.header-tools{gap:10px}.chapter-toggle{font-size:11px;padding:6px 9px}.brand.physics-brand{font-size:15px}.motion{font-size:9px}.header-inner{padding:0 12px;gap:10px}
}
.course-directory .minimal-topic-title{font-size:15.2px;font-weight:800;min-width:0;flex:1}

/* Line Vector Builder Controls */
.line-builder{margin-top:14px;padding:12px 14px;background:#f8fafc;border:1px solid #e2e8f0;border-radius:8px;display:flex;flex-direction:column;gap:10px}
.builder-row{display:flex;align-items:center;justify-content:space-between;gap:12px;flex-wrap:wrap}
.builder-col{display:flex;flex-direction:column;gap:4px;flex:1;min-width:210px}
.builder-title{font-size:12px;font-weight:700;color:#475569;text-transform:uppercase;letter-spacing:.5px}
.builder-inputs{display:flex;align-items:center;gap:6px}
.builder-inputs input[type="number"]{width:56px;height:34px;text-align:center;font-size:15px;font-weight:700;border:1px solid #cbd5e1;border-radius:6px;background:#fff;color:#0f172a}
.builder-inputs .button{padding:4px 9px;font-size:13px;font-weight:600;min-height:34px}
.builder-plus{font-size:24px;font-weight:700;color:#64748b;margin-top:16px}
.builder-presets{display:flex;align-items:center;gap:6px;flex-wrap:wrap;padding-top:6px;border-top:1px dashed #cbd5e1}
.builder-presets .button.small{padding:3px 9px;font-size:12px}

/* Number explorers share the Physics card shell and typography. */
.number-explorer {min-width:0;}
.number-explorer > label {display:block;font-weight:600;margin-bottom:8px;}
.number-explorer > select {width:100%;max-width:100%;margin-bottom:12px;padding:10px 12px;border:1px solid #bdcde1;border-radius:8px;background:white;color:#0b2545;font:inherit;}
.number-explorer figure {margin:0;}
.number-explorer-svg {display:block;width:100%;height:auto;max-width:100%;font-family:Inter,sans-serif;}
.number-explorer figcaption {font-size:14px;line-height:1.65;color:var(--muted,#42597a);margin:12px 0;}
.number-explorer .controls {flex-wrap:wrap;}
.exact-steps {padding:16px 0;}
.exact-steps p {font-family:Outfit,Inter,sans-serif;font-size:clamp(17px,1.7vw,23px);line-height:1.7;overflow-wrap:anywhere;}
.pathway {grid-template-columns:repeat(auto-fit,minmax(155px,1fr));}
@media (max-width:760px) {.number-explorer .controls .button {font-size:13px;padding:9px 10px;} .number-explorer-svg {min-height:160px;} }

/* Compact Pickers for Signed Numbers & Pizza */
.compact-vector-picker, .compact-place-picker{display:flex;align-items:center;justify-content:center;gap:12px;flex-wrap:wrap;margin-top:14px;padding:12px 16px;background:#f8fafc;border:1px solid #e2e8f0;border-radius:8px}
.picker-card{display:flex;flex-direction:column;align-items:center;gap:4px}
.picker-label{font-size:11px;font-weight:700;color:#64748b;text-transform:uppercase;letter-spacing:.5px}
.picker-controls{display:flex;align-items:center;gap:5px}
.picker-select{height:38px;padding:0 8px;font-size:17px;font-weight:700;font-family:inherit;border:1.5px solid #cbd5e1;border-radius:6px;background:#fff;color:#0f172a;cursor:pointer;text-align:center;transition:border-color .15s,box-shadow .15s}
.picker-select:focus{border-color:#2563eb;outline:none;box-shadow:0 0 0 3px rgba(37,99,235,.15)}
.sign-select{width:52px;color:#2563eb}
.num-select{width:56px}
.picker-operator,.picker-equals,.picker-point{font-size:24px;font-weight:700;color:#64748b;margin-top:14px}
.result-card{min-width:75px}
.picker-result-val{height:38px;padding:0 12px;display:flex;align-items:center;justify-content:center;font-size:19px;font-weight:700;color:#047857;background:#ecfdf5;border:1.5px solid #10b981;border-radius:6px}
.picker-slice-btn{display:flex;gap:6px;margin-top:14px}
.picker-slice-btn .button{min-height:38px;padding:0 14px;font-size:13.5px;font-weight:600}

/* Floating Circular Replay Button on Canvas */
.canvas-lesson{position:relative}
.canvas-replay-btn{position:absolute;right:14px;bottom:14px;width:38px;height:38px;border-radius:50%;background:rgba(255,255,255,0.92);border:1.5px solid #cbd5e1;color:#1e293b;display:flex;align-items:center;justify-content:center;cursor:pointer;box-shadow:0 2px 8px rgba(0,0,0,0.10);transition:all .18s ease;z-index:5}
.canvas-replay-btn:hover{background:#fff;border-color:#2563eb;color:#2563eb;transform:scale(1.10);box-shadow:0 4px 12px rgba(37,99,235,0.22)}
.canvas-replay-btn:active{transform:scale(0.96)}

.canvas-step-controls{display:flex;flex-wrap:wrap;gap:8px;margin-top:10px}.canvas-step-controls .button{flex:1;white-space:nowrap}.canvas-lesson .canvas-narration{font-size:14px;line-height:1.6}.canvas-transport label{min-width:0}

.place-builder{margin-top:18px;padding:16px;border:1px solid #dce6f2;border-radius:12px;background:#fff}
.place-builder-heading{display:flex;flex-wrap:wrap;justify-content:space-between;gap:4px 12px;font-size:14px;color:#17334b}
.place-builder-heading span{color:#647487;font-size:12px}
.place-builder .compact-place-picker{margin:12px 0;background:#f8fbff;padding:14px 10px;gap:10px}
.place-builder .place-stepper{gap:5px;min-width:54px}
.place-stepper input{width:54px;height:44px;padding:4px;text-align:center;border:1px solid #bdcee3;border-radius:7px;background:#fff;color:#17334b;font:700 22px Inter,sans-serif;appearance:textfield;-moz-appearance:textfield}
.place-stepper input::-webkit-inner-spin-button,.place-stepper input::-webkit-outer-spin-button{-webkit-appearance:none;margin:0}
.place-step-button{width:54px;min-height:34px;border:1px solid #d6e1f0;border-radius:7px;background:#edf4fe;color:#1557c7;font:700 13px Inter,sans-serif}
.place-step-button:hover:not(:disabled){background:#dceaff}
.place-step-button:disabled{opacity:.35}
.place-builder .result-card{min-width:64px}
.place-builder .place-recalculate{width:100%;min-height:44px;font-size:14px}
.place-builder-status{margin:10px 0 0;min-height:2.8em;color:#42597a;font-size:13px;line-height:1.5}
#place-visual{scroll-margin-top:80px}
@media(max-width:400px){.place-builder{padding:12px}.place-builder .compact-place-picker{gap:6px;padding:12px 6px}.place-builder .picker-point,.place-builder .picker-equals{font-size:22px}.place-step-button{min-height:40px}}

/* Keep the mathematics larger than its controls. */
.place-animation{position:relative}
.place-replay{position:absolute;right:5px;top:3px;display:grid;place-items:center;width:32px;height:32px;padding:0;border:1px solid #d7e3f2;border-radius:50%;background:#fff;color:#1557c7;font:22px/1 Inter,sans-serif;cursor:pointer}
.place-replay:hover{background:#edf4fe}
.place-builder{margin-top:8px;padding:10px 12px;border-radius:8px}
.place-builder-row{display:flex;flex-wrap:wrap;align-items:flex-end;justify-content:center;gap:8px}
.place-builder .place-stepper{display:flex;flex-direction:column;align-items:flex-start;gap:3px;min-width:0}
.place-digit-control{display:flex;align-items:stretch;gap:3px}
.place-stepper input{width:42px;height:38px;font-size:20px}
.place-arrow-pair{display:flex;flex-direction:column;gap:2px}
.place-builder .place-step-button{width:24px;min-height:18px;height:18px;border-radius:4px;padding:0;font-size:12px;line-height:1}
.place-builder .picker-point{align-self:flex-end;padding-bottom:6px;font-size:22px}
.place-builder .place-recalculate{width:auto;min-height:38px;padding:6px 14px;font-size:13px}
.place-builder-status{margin:6px 0 0;min-height:0;font-size:12px;line-height:1.4;text-align:center}
@media(pointer:coarse){.place-arrow-pair{gap:0}.place-builder .place-step-button{height:24px;min-height:24px;width:28px}.place-stepper input{height:48px}}
@media(max-width:400px){.place-builder{padding:8px}.place-builder-row{gap:6px}.place-builder .place-recalculate{padding:6px 10px}}

.compact-vector-picker{padding:8px;gap:8px;margin-top:8px;background:#fff}
.compact-vector-picker .picker-controls{gap:4px}
.compact-vector-picker .picker-operator{font-size:18px;margin-top:14px}
.line-sign-button{width:28px;height:38px;border:1px solid #bdcee3;border-radius:6px;background:#edf4fe;color:#1557c7;font:700 20px Inter,sans-serif;cursor:pointer}
.line-stepper input{appearance:textfield;-moz-appearance:textfield;width:36px;height:38px;text-align:center;border:1px solid #bdcee3;border-radius:6px;padding:2px;background:#fff;color:#17334b;font:700 20px Inter,sans-serif}
.line-stepper input::-webkit-inner-spin-button,.line-stepper input::-webkit-outer-spin-button{-webkit-appearance:none;margin:0}
.line-stepper .place-step-button{width:22px;min-height:18px;height:18px;padding:0;font-size:12px;line-height:1;border-radius:4px}
@media(pointer:coarse){.line-stepper .place-step-button{min-height:24px;height:24px}.line-stepper input,.line-sign-button{height:48px}}
/* Algebra uses the same lesson layout and small, focused SVG controls. */
.algebra-summary{margin:20px 0 24px;padding:18px 22px;border:1px solid #d7e3f2;border-radius:10px;background:#f4f8fe}
.algebra-summary h2{margin:0 0 10px;font-size:20px}
.algebra-summary ul{margin:0;padding-left:22px;line-height:1.7}
.algebra-worked{margin:16px 0;padding-left:27px;font-size:clamp(17px,1.5vw,22px);line-height:1.65;overflow-wrap:anywhere}
.algebra-worked li{padding:9px 0 9px 5px;border-bottom:1px solid #dbe3ed}
.algebra-explorer figure{margin:12px 0 0;min-width:0}
.algebra-explorer svg{display:block;width:100%;height:auto;max-height:340px}
.algebra-explorer figcaption{margin-top:12px;font-size:14px;line-height:1.6;min-height:3em}
.algebra-inputs{display:flex;flex-wrap:wrap;gap:12px;margin-top:14px}
.algebra-inputs label{display:flex;align-items:center;gap:8px;font-size:14px;font-weight:600;min-width:0}
.algebra-inputs input{width:72px;min-height:40px;padding:6px;border:1px solid #b7c7dc;border-radius:6px;background:#fff;font:inherit;font-size:18px}
.algebra-inputs select{max-width:100%;min-height:40px;border:1px solid #b7c7dc;border-radius:6px;background:#fff;padding:6px;font:inherit}
.algebra-connections{margin:24px 0 32px}
.algebra-connections h2{font-size:22px;margin-bottom:6px}
.algebra-connections ol{list-style:none;padding:0;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}
.algebra-connections li{padding:16px;border-left:3px solid #285caf;background:#f0f5fc;display:flex;flex-direction:column;gap:7px;line-height:1.5}
.algebra-unit-card{display:block;color:inherit;text-decoration:none;position:relative;transition:background-color 150ms ease-out,border-color 150ms ease-out}
.algebra-unit-card:hover{background:#e8f0fc;border-color:#285caf}
.algebra-unit-card:focus-visible{outline:3px solid #285caf;outline-offset:3px}
.algebra-unit-symbol{float:right;color:#285caf;font:24px Georgia,serif;margin-left:12px}
.course-details{font-size:14px;line-height:1.5;color:#53637a}
.course-details summary{cursor:pointer;font-weight:600;padding:8px 0}
.course-details p{margin:4px 0 10px}
@media(max-width:640px){.algebra-connections ol{grid-template-columns:1fr}.algebra-inputs label{flex-wrap:wrap}.algebra-inputs select{width:100%}.algebra-worked{font-size:17px}.algebra-explorer .controls{gap:7px}.algebra-explorer .controls .button{padding:9px 10px}}
@media(prefers-reduced-motion:reduce){.algebra-unit-card{transition:none}}
@media(max-width:640px){.algebra-explorer:is([data-algebra="line"],[data-algebra="quadratic"],[data-algebra="families"],[data-algebra="intersection"]) svg text{font-size:24px}}
@media(max-width:640px){.ratio-explorer:is([data-ratio="direct"],[data-ratio="inverse"],[data-ratio="power"],[data-ratio="speed"],[data-ratio="tangent"]) svg text{font-size:24px}}
/* Visual-first pilot: the subtitle and calculation live inside one teaching frame. */
.visual-story-section .section-head{align-items:center}
.visual-story-section .section-head h2{margin-bottom:0}
.story-lesson{padding:18px 22px;display:grid;grid-template-columns:auto minmax(0,1fr);gap:14px;min-width:0}
.story-top{grid-column:1/-1;display:flex;align-items:center;justify-content:space-between;gap:12px}
.story-task{font-size:17px;font-weight:600;line-height:1.5;margin:0}
.story-count{font-size:12px;font-variant-numeric:tabular-nums;white-space:nowrap;color:#53677f}
.story-frame{grid-column:1/-1;margin:0;border:1px solid #d4e1f0;border-radius:10px;overflow:hidden;background:#f8fbff;min-width:0}
.story-art{width:100%;max-width:680px;margin:0 auto;padding:6px 0 0}
.story-art svg{display:block;width:100%;height:auto;max-height:260px;overflow:visible}
.story-subtitle{font-size:17px;font-weight:600;line-height:1.5;text-align:center;padding:10px 18px;min-height:52px;color:#173b69;background:#edf4ff}
.story-maths{list-style:none;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));align-content:start;gap:5px 20px;max-width:780px;margin:0 auto;padding:12px 18px;font-size:17px;line-height:1.65;min-height:88px;font-variant-numeric:tabular-nums}
[data-story="share"] .story-maths{min-height:120px}
.story-maths li{overflow-wrap:anywhere}
.story-maths li:last-child:nth-child(odd){grid-column:1/-1}
.story-maths li[hidden]{display:none}
.story-maths .is-new{color:#1955a8;font-weight:650}
.story-transport{display:flex;gap:6px;align-items:center;align-self:center;flex-wrap:wrap}
.story-transport .button{min-height:40px;padding:8px 11px;font-size:13px;line-height:1.3;white-space:nowrap;touch-action:manipulation}
.story-transport .story-previous,.story-transport .story-replay{width:40px;padding:8px 0;font-size:19px}
.story-transport .story-play{min-width:76px;font-variant-numeric:tabular-nums}
.story-inputs{display:flex;justify-content:flex-end;align-items:center;gap:12px;flex-wrap:wrap}
.story-inputs label{font-size:12px;color:#53677f;display:flex;align-items:center;gap:7px;font-weight:600}
.story-inputs input{width:66px;min-height:40px;padding:6px;border:1px solid #b7c7dc;border-radius:6px;background:white;color:#17334b;font:600 18px Inter,sans-serif}
.story-validation,.story-rounding,.story-motion-hint{grid-column:1/-1;margin:0;font-size:13px;line-height:1.5;color:#53677f}
.story-validation{color:#87521d}
.story-lesson [hidden]{display:none!important}
.story-why{border-top:1px solid #dbe5f1;padding:0 22px 14px;color:#38506f;font-size:14px;line-height:1.65}
.story-why summary{cursor:pointer;padding:12px 0 0;color:#1955a8;font-size:14px;font-weight:600;width:max-content;min-height:40px}
.story-why p{max-width:85ch;margin:10px 0}
@media(max-width:1100px){.story-lesson{grid-template-columns:1fr}.story-inputs{justify-content:flex-start}.story-top,.story-frame{grid-column:1}}
@media(max-width:640px){.story-lesson{padding:14px 12px;gap:12px}.story-task{font-size:16px}.story-subtitle{padding:10px 12px;min-height:92px;font-size:16px;text-align:left}.story-maths{grid-template-columns:1fr;padding:10px 12px;font-size:16px;gap:2px;min-height:126px}[data-story="share"] .story-maths{min-height:158px}.story-art svg text{font-size:34px}.story-art svg [data-story-group] text{font-size:30px}.story-transport{gap:5px}.story-transport .button{font-size:12px;padding:8px 9px}.story-transport .story-previous,.story-transport .story-replay{width:36px;font-size:18px}.story-transport .story-play{min-width:70px}.story-inputs{gap:10px}.story-inputs label{flex-direction:column;align-items:flex-start;gap:3px}.story-inputs input{width:64px}.story-why{padding:0 14px 12px}}
@media(pointer:coarse){.story-transport .button,.story-inputs input{min-height:44px}}

/* Keep the action, model and live explanation together. No animation delay on inputs. */
.interactive-note .note-grid{grid-template-columns:minmax(0,1fr);gap:14px}
.interactive-note .note-copy{max-width:none}
.interactive-note .note-copy ul{display:block}
.algebra-explorer figure.explorer-frame,.later-explorer figure.explorer-frame{display:grid;grid-template-columns:minmax(0,1fr) minmax(230px,.43fr);align-items:center;gap:16px;margin:10px 0 0}
.explorer-plot,.explorer-panel{min-width:0}
.algebra-explorer .explorer-panel,.later-explorer .explorer-panel,.place-explorer .explorer-panel{margin:0;padding:14px;background:#edf3fc;border:1px solid #c8d8ed;border-radius:8px;font-size:15px;line-height:1.55;min-height:0}
.explorer-panel .algebra-inputs{margin:0;display:grid;gap:10px}
.explorer-panel .algebra-inputs label{justify-content:space-between;flex-wrap:wrap}
.explorer-panel input,.explorer-panel select{max-width:100%}
.explorer-panel .explorer-feedback{font-size:15px;line-height:1.6;margin:12px 0 0;font-variant-numeric:tabular-nums;overflow-wrap:anywhere}
.explorer-panel .controls{display:flex;flex-wrap:wrap;gap:6px;margin-top:12px}
.explorer-panel .controls .button{min-height:40px;padding:7px 9px}
.explorer-worked{margin-top:12px;border-top:1px solid #d5e1ef;font-size:14px}
.explorer-worked summary{cursor:pointer;padding:10px 0;font-weight:600;color:#285caf}
.explorer-worked .algebra-worked{font-size:16px;margin:8px 0}
.place-explorer{display:grid;grid-template-columns:minmax(0,1fr) minmax(230px,.43fr);align-items:center;gap:16px}
.place-meaning strong{font-size:18px;color:#1557c7}.place-meaning p{font-size:14px;line-height:1.5;margin:8px 0 12px}
.place-explorer .place-builder{margin:0;padding:0;border:0;background:none}
.place-explorer .place-builder-row{flex-wrap:wrap;justify-content:flex-start}
.place-transport{display:flex;flex-wrap:wrap;gap:8px;border-top:1px solid #c8d8ed;margin-top:12px;padding-top:12px}
.place-transport label{flex-basis:100%;font-size:13px}.place-transport input{display:block;width:100%;min-height:36px;accent-color:#1557c7}.place-transport output{font-size:13px;font-variant-numeric:tabular-nums}
@media(max-width:760px){.algebra-explorer figure.explorer-frame,.later-explorer figure.explorer-frame,.place-explorer{grid-template-columns:minmax(0,1fr);gap:8px}.algebra-explorer .explorer-panel,.later-explorer .explorer-panel,.place-explorer .explorer-panel{padding:12px}.explorer-panel .algebra-inputs{display:flex;flex-wrap:wrap;gap:8px 14px}.explorer-panel .explorer-feedback{margin-top:8px}.interactive-note .diagram{padding:10px}.place-transport{margin-top:8px;padding-top:8px}}