.number-playground{--number-playground-rod-length:11.25rem;font-family:var(--font-ui);padding:var(--space-3);border-radius:var(--radius-feature);background:var(--surface-raised);border:0;min-inline-size:0}@container teaching-workspace (width>=30rem){.number-playground[data-playground-kind=count] .number-playground__objects:not(.number-playground__objects--frame){justify-content:center;gap:var(--space-2);min-block-size:8rem}.number-playground[data-playground-kind=count] .number-playground__objects:not(.number-playground__objects--frame) .number-playground__item{min-block-size:3.75rem;min-inline-size:3.75rem}.number-playground[data-playground-kind=count] .number-playground__objects:not(.number-playground__objects--frame) .number-playground__item--dot:before{block-size:3.25rem;inline-size:3.25rem}.number-playground[data-playground-kind=count] .number-playground__item>span{font-size:var(--type-control)}}:is([data-step-view=stages],[data-teaching-stage-active]) .number-playground[data-playground-kind=count] .number-playground__group{background:0 0;border:0}.teaching-layout__visual .number-playground{background:0 0;padding:0}.number-playground__groups{gap:var(--space-2);align-items:stretch;display:grid}.number-playground[data-playground-kind=equal-groups] .number-playground__groups{grid-template-columns:repeat(auto-fit,minmax(min(7rem,100%),1fr))}.number-playground[data-playground-kind=equal-groups] .number-playground__objects{place-content:start;gap:var(--space-1);grid-template-columns:repeat(2,max-content);min-block-size:2.5rem;display:grid}.number-playground[data-playground-kind=equal-groups] .number-playground__item{min-block-size:1.5rem;min-inline-size:1.5rem}.number-playground[data-playground-kind=equal-groups] .number-playground__item--dot:before{block-size:1.5rem;inline-size:1.5rem}.number-playground[data-playground-kind=join] .number-playground__groups,.number-playground[data-playground-kind=partition] .number-playground__groups,.number-playground[data-playground-kind=compare] .number-playground__groups,.number-playground[data-playground-kind=base-ten] .number-playground__groups,.number-playground[data-playground-kind=calculate] .number-playground__groups{grid-template-columns:repeat(2,minmax(0,1fr))}.number-playground__objects:has(>.number-playground__item--ten){gap:var(--space-1);grid-template-columns:repeat(auto-fit,minmax(2.75rem,1fr));display:grid}.number-playground[data-playground-kind=sharing] .number-playground__groups{grid-template-columns:repeat(2,minmax(0,1fr))}.number-playground[data-playground-kind=sharing] .number-playground__group:first-child{grid-column:1/-1}.number-playground__group{padding:var(--space-2);border:1px solid var(--divider-quiet);border-radius:var(--radius-control);background:var(--surface-raised);min-inline-size:0}.number-playground__label{font-size:var(--type-prose);margin:0 0 var(--space-2);font-weight:700}.number-playground__objects{gap:var(--space-0);flex-wrap:wrap;align-items:center;min-block-size:5rem;display:flex}.number-playground__objects--spread{gap:.9rem}.number-playground[data-playground-kind=compare] .number-playground__objects{grid-template-columns:minmax(2.75rem,1fr);justify-items:center;display:grid}.number-playground[data-playground-kind=compare] .number-playground__item.is-marked{outline:2px solid var(--accent-700);outline-offset:-2px}.number-playground[data-playground-kind=compare] .number-playground__item.is-marked>span:not(:empty){text-decoration:underline}.number-playground__objects--spread>:nth-child(3n+1){margin-block-start:1rem}.number-playground__objects--spread>:nth-child(3n+2){margin-block-end:1rem}.number-playground__group.is-related{border-style:solid;border-color:var(--accent-600);background:var(--accent-100)}.number-playground__item.is-related{outline:3px solid var(--accent-600);outline-offset:-1px}.number-playground__equation button{font:inherit;color:inherit;background:var(--paper-0);border:1px solid var(--ink-500);border-radius:var(--radius-control);cursor:pointer;min-block-size:3rem;min-inline-size:3rem;padding-inline:var(--space-2)}.number-playground__equation button[aria-pressed=true]{outline:3px solid var(--accent-600);text-decoration:underline}.number-playground__equation button:focus-visible{outline:3px solid var(--accent-600);outline-offset:2px}.number-playground__links{gap:var(--space-2);margin-block:var(--space-3);flex-wrap:wrap;display:flex}.number-playground__links button[aria-pressed=true]{border:2px solid var(--accent-600);text-decoration:underline}.number-playground__objects--frame{border:1px solid var(--ink-500);grid-template-columns:repeat(5,minmax(0,1fr));gap:0;max-inline-size:20rem;display:grid}.number-playground__objects--frame>*{border:1px solid var(--ink-500);border-radius:0;inline-size:100%;min-inline-size:0}.number-playground__item{vertical-align:middle;min-block-size:2.75rem;min-inline-size:2.75rem;color:var(--ink-900);border-radius:var(--radius-control);font:inherit;background:0 0;border:2px solid #0000;flex:none;justify-content:center;align-items:center;padding:0;font-weight:700;display:inline-flex;position:relative}button.number-playground__item{cursor:pointer;touch-action:manipulation}button.number-playground__item:hover{border-color:var(--accent-500)}button.number-playground__item:focus-visible{outline:3px solid var(--accent-500);outline-offset:2px}.number-playground__item--dot:before,.number-playground__item--ring:before{content:"";box-sizing:border-box;border:2px solid var(--accent-700);background:var(--accent-200);border-block-end-width:5px;border-radius:50%;block-size:2.25rem;inline-size:2.25rem}.number-playground__item--ring:before{background:var(--surface-raised);border-width:6px;border-color:var(--warning-700)}.number-playground__item--dot>span,.number-playground__item--ring>span{color:var(--text-primary);font-size:1.125rem;line-height:1;position:absolute}.number-playground__item--dot.is-marked:before{background:var(--accent-700);border-color:var(--accent-700)}.number-playground__item--card{border-color:var(--control-boundary);background:var(--surface-raised);font-size:var(--type-subsection);padding-inline:var(--space-3);border-block-end-width:5px}.number-playground__item--card.is-marked{border:3px solid var(--accent-500);text-decoration:underline}.number-playground__rod{inline-size:var(--number-playground-rod-length);box-sizing:border-box;border:1px solid var(--accent-700);block-size:1.125rem;max-inline-size:100%;display:inline-flex}.number-playground__rod>span{background:var(--accent-200);border-inline-end:1px solid var(--accent-700);flex:1}.number-playground__rod>span:last-child{border:0}.number-playground__item--ten>.number-playground__rod{inline-size:1.125rem;block-size:var(--number-playground-rod-length);flex-direction:column}.number-playground__item--ten>.number-playground__rod>span{border-inline-end:0;border-block-end:1px solid var(--accent-700)}.number-playground__item--ten>.number-playground__rod>span:last-child{border-block-end:0}.number-playground__hundred{inline-size:var(--number-playground-rod-length);aspect-ratio:1;box-sizing:border-box;border:1px solid var(--accent-700);flex-direction:column;max-inline-size:100%;display:flex}.number-playground__item--hundred,.number-playground__item--ten,.number-playground__item--one{border:0;min-block-size:0;min-inline-size:0;max-inline-size:100%}button.number-playground__item--ten,button.number-playground__item--hundred{min-block-size:2.75rem;min-inline-size:2.75rem;padding:var(--space-1);border:1px dashed var(--control-boundary)}button.number-playground__item--ten{justify-self:center;inline-size:2.75rem}.number-playground__unit{box-sizing:border-box;border:1px solid var(--accent-700);background:var(--accent-200);block-size:1.125rem;inline-size:1.125rem}.number-playground__hundred>.number-playground__rod{border:0;border-block-end:1px solid var(--accent-700);flex:1;block-size:auto;min-block-size:0;inline-size:100%}.number-playground__hundred>.number-playground__rod:last-child{border-block-end:0}.number-playground__equation{text-align:center;margin-block:var(--space-3);overflow-wrap:anywhere;font-size:1.25rem;font-weight:700}.number-playground__actions{gap:var(--space-2);flex-wrap:wrap;margin-block-start:var(--space-3);display:flex}.number-playground__tools{font-size:var(--type-meta);flex:1 0 100%}.number-playground__tools summary{min-block-size:var(--control-height);cursor:pointer;color:var(--text-secondary);align-items:center;display:flex}.number-playground__tools summary:before{content:"+";margin-inline-end:var(--space-1);font-weight:700}.number-playground__tools[open] summary:before{content:"−"}.number-playground__tools summary:focus-visible{outline:3px solid var(--focus-ring-color);outline-offset:2px}.number-playground [data-playground-observation]{font-size:var(--type-meta);line-height:var(--leading-ui)}.number-playground [hidden]{display:none!important}@media (width<=40rem){.number-playground__group{padding:var(--space-2)}.number-playground__objects{min-block-size:3.5rem}.number-playground__equation{font-size:var(--type-control)}}.number-playground__destination{justify-content:space-between;align-items:center;gap:var(--space-1);inline-size:100%;min-block-size:var(--control-height);padding:var(--space-1) var(--space-2);background:var(--selected-bg);color:var(--selected-fg);border:1px solid var(--control-boundary);border-radius:var(--radius-control);font:700 var(--type-control) / var(--leading-ui) var(--font-ui);cursor:pointer;touch-action:manipulation;flex-wrap:wrap;margin-block-end:var(--space-2);display:flex}.number-playground__destination-hint{font-size:var(--type-meta);font-weight:500}.number-playground__destination:focus-visible{outline:3px solid var(--focus-ring-color);outline-offset:2px}.number-playground .is-cued{outline:3px solid var(--accent-600);outline-offset:2px}.number-playground__group.is-cued{border-style:dashed;border-color:var(--accent-600)}.number-playground__direction{font-size:var(--type-control);color:var(--selected-fg);font-weight:700}.number-playground__direction--right{text-align:right}.number-playground__jump{font-size:var(--type-control);color:var(--text-secondary)}.number-playground__next-card{border-style:dashed}@media (prefers-reduced-motion:no-preference){button.number-playground__item:active{transform:translateY(2px)}.number-playground__item.is-marked{animation:counter-touch var(--motion-standard) ease-out}@keyframes counter-touch{50%{transform:scale(1.12)}}}.number-playground__actions:empty,.number-playground__actions[hidden]{display:none}.number-playground[data-playground-kind=sharing] .number-playground__group .family-button{inline-size:100%;padding-inline:var(--space-1);font-size:1rem}@media (forced-colors:active){.number-playground .is-cued{outline-color:highlight}.number-playground__item--dot:before,.number-playground__item--dot.is-marked:before{forced-color-adjust:none;background:canvastext;border-color:canvastext}.number-playground__item--ring:before{forced-color-adjust:none;background:canvas;border-color:canvastext}.number-playground__item--dot>span{forced-color-adjust:none;color:canvas}button.number-playground__item:focus-visible{outline-color:highlight}}.number-playground__empty{color:var(--ink-700);font-size:var(--type-prose)}.number-playground[data-playground-ready] [data-playground-board] button[data-playground-action]:disabled{display:none}.number-playground[data-playground-kind=calculate] [data-playground-board]>.number-playground__actions{grid-template-columns:repeat(2,minmax(0,1fr));display:grid}.number-playground[data-playground-kind=calculate] [data-playground-board]>.number-playground__actions button{font-size:var(--type-meta);padding-inline:var(--space-1)}@media print{.number-playground__item,.number-playground__equation button{display:inline-flex!important}.number-playground__equation button{border:0;min-block-size:0;min-inline-size:0;padding:0}.number-playground__actions,.number-playground__links{display:none}.number-playground__group{break-inside:avoid}.number-playground__next-card,.number-playground__destination-hint{display:none!important}}.number-playground__item--ten-group{padding:var(--space-2);border:2px solid var(--control-boundary);border-radius:var(--radius-control);background:var(--surface-raised);position:relative}.number-playground__ten-group{grid-template-columns:repeat(5,.75rem);gap:.4rem;display:grid}.number-playground__ten-group>span{background:var(--accent-600);border:1px solid;border-radius:50%;block-size:.75rem;inline-size:.75rem}.number-playground__batch-mark{background:var(--surface-raised);font-weight:700;position:absolute;inset-block-start:-.5rem;inset-inline-end:-.4rem}.number-playground__progress{gap:var(--space-1);font-size:var(--type-meta);margin-block-end:var(--space-2);display:grid}.number-playground__progress-spaces{gap:var(--space-1);flex-wrap:wrap;display:flex}.number-playground__progress-spaces>span{border:2px dashed var(--control-boundary);border-radius:50%;place-items:center;block-size:1.5rem;inline-size:1.5rem;display:grid}.number-playground__progress-spaces>.is-filled{background:var(--accent-100);border-style:solid;font-weight:700}.number-playground[data-playground-kind=friendly-groups] .number-playground__groups{grid-template-columns:repeat(auto-fit,minmax(min(9rem,100%),1fr))}.number-playground[data-playground-kind=friendly-groups] .number-playground__group:has(button[aria-pressed=true]){outline:2px solid var(--accent-700);outline-offset:-2px}@media print{.number-playground__progress{display:none}}.number-playground[data-playground-places="3"]{--place-cell:.375rem}.number-playground[data-playground-places="3"] .number-playground__groups{grid-template-columns:repeat(3,minmax(0,1fr));align-items:start}.number-playground[data-playground-places="3"] .number-playground__objects{align-content:flex-start;align-items:flex-start;gap:var(--space-0);min-block-size:calc(var(--place-cell) * var(--place-radix));display:flex}.number-playground[data-playground-places="3"] .number-playground__hundred{inline-size:calc(var(--place-cell) * var(--place-radix));block-size:calc(var(--place-cell) * var(--place-radix));max-inline-size:none}.number-playground[data-playground-places="3"] .number-playground__item--ten>.number-playground__rod{inline-size:var(--place-cell);block-size:calc(var(--place-cell) * var(--place-radix))}.number-playground[data-playground-places="3"] .number-playground__unit{inline-size:var(--place-cell);block-size:var(--place-cell)}.number-playground[data-playground-places="3"] .number-playground__equation button{min-block-size:2.75rem;min-inline-size:2.75rem;padding-inline:var(--space-0)}@media (width<=40rem){.number-playground[data-playground-places="3"] .number-playground__groups{grid-template-columns:minmax(0,1fr)}}.number-playground[data-playground-rod-orientation=horizontal] .number-playground__groups{grid-template-columns:repeat(auto-fit,minmax(min(100%,13rem),1fr))}.number-playground[data-playground-rod-orientation=horizontal] .number-playground__objects:has(>.number-playground__item--ten){align-items:start;gap:var(--space-2);flex-direction:column;display:flex}.number-playground[data-playground-rod-orientation=horizontal] .number-playground__item--ten>.number-playground__rod{inline-size:var(--number-playground-rod-length);flex-direction:row;block-size:1.125rem}.number-playground[data-playground-rod-orientation=horizontal] .number-playground__item--ten>.number-playground__rod>span{border-block-end:0;border-inline-end:1px solid var(--accent-700)}.number-playground[data-playground-rod-orientation=horizontal] .number-playground__item--ten>.number-playground__rod>span:last-child{border-inline-end:0}@media (forced-colors:active),print{.number-playground__rod>span,.number-playground__unit{forced-color-adjust:none;print-color-adjust:exact;background:repeating-linear-gradient(135deg,canvas 0 5px,canvastext 5px 6px);border-color:canvastext}}