:root{font-family:-apple-system,BlinkMacSystemFont,'Hiragino Kaku Gothic ProN','Yu Gothic',system-ui,sans-serif;color:#18342d;background:#f7f4ea;font-synthesis:none;--ink:#173f35;--paper:#fffdf7;--cream:#f7f4ea;--coral:#e25d3d;--yellow:#f3c94d;--line:#d9d7ca}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;min-width:320px;min-height:100vh;background:var(--cream)}button,input,select{font:inherit}button,a{-webkit-tap-highlight-color:transparent}a{color:inherit}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible{outline:4px solid #267cbd;outline-offset:3px}.app{min-height:100vh}.offline-banner{padding:10px 24px;color:#fff;background:#86540f;text-align:center;font-weight:700}
.site-header{height:78px;display:flex;align-items:center;justify-content:space-between;padding:0 max(28px,calc((100vw - 1180px)/2));background:rgba(255,253,247,.95);border-bottom:1px solid var(--line);position:relative;z-index:5}.brand{display:flex;align-items:center;gap:11px;text-decoration:none;font-weight:900;font-size:20px;letter-spacing:.04em}.brand-mark{display:grid;place-items:center;width:36px;height:36px;border-radius:10px;color:var(--paper);background:var(--coral);transform:rotate(-3deg)}nav{display:flex;align-items:center;gap:8px}nav a{padding:10px 14px;border-radius:99px;text-decoration:none;font-size:14px;font-weight:700}nav a:hover,nav a[aria-current=page]{background:#e5eee8}
.hero{min-height:490px;display:grid;grid-template-columns:1.03fr .97fr;align-items:center;gap:60px;padding:72px max(28px,calc((100vw - 1120px)/2));overflow:hidden;background:var(--ink);color:#fff;position:relative}.hero:after{content:'';position:absolute;width:420px;height:420px;right:-150px;top:-180px;border:70px solid rgba(243,201,77,.12);border-radius:50%}.eyebrow{display:inline-block;margin-bottom:14px;color:var(--coral);font-size:12px;line-height:1;font-weight:900;letter-spacing:.18em;text-transform:uppercase}.hero .eyebrow{color:var(--yellow)}.hero h1{margin:0;font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:clamp(52px,7vw,84px);line-height:1.13}.hero h1 em{color:var(--yellow);font-style:normal}.hero-copy p{max-width:540px;margin:28px 0 0;color:#d9e6df;font-size:17px;line-height:1.9}.hero-visual{display:flex;align-items:center;justify-content:center;gap:12px;min-height:330px;position:relative;z-index:1}.number-card{width:112px;height:144px;display:grid;place-items:center;border-radius:20px;background:var(--paper);color:var(--ink);box-shadow:0 14px 0 rgba(0,0,0,.18);font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:76px;font-weight:900}.card-one{transform:rotate(-8deg)}.card-two{transform:rotate(6deg);background:#e9cfc3}.operator{font-size:38px;font-weight:900}.answer-bubble{width:130px;height:130px;display:grid;place-content:center;border-radius:50%;background:var(--yellow);color:var(--ink);text-align:center;font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:64px;font-weight:900;transform:rotate(-5deg)}.answer-bubble span{display:block;font-size:12px}
.path-section{max-width:1120px;margin:0 auto;padding:82px 28px 95px}.section-heading{text-align:center;margin-bottom:38px}.section-heading span{color:var(--coral);font-size:11px;font-weight:900;letter-spacing:.2em}.section-heading h2{margin:10px 0 0;font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:32px}.path-grid{display:grid;grid-template-columns:1fr 1fr;gap:24px}.path-card{min-height:320px;padding:34px;border:0;border-radius:18px;color:var(--ink);text-align:left;cursor:pointer;position:relative;overflow:hidden;text-decoration:none;transition:transform .2s,box-shadow .2s}.path-card:hover{transform:translateY(-5px);box-shadow:0 18px 32px rgba(23,63,53,.13)}.teacher-card{background:#e5eee8}.learner-card{background:#f5d9ce}.path-number{position:absolute;right:26px;top:20px;color:rgba(23,63,53,.16);font-size:68px;font-weight:900}.path-icon{display:grid;place-items:center;width:62px;height:62px;margin-bottom:25px;border-radius:17px;color:#fff;background:var(--ink);font-size:28px;transform:rotate(-4deg)}.learner-card .path-icon{background:var(--coral);transform:rotate(4deg)}.path-card strong{display:block;font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:28px}.path-card>span:not(.path-icon):not(.path-number){display:block;margin-top:5px;font-weight:700}.path-card small{display:block;margin-top:18px;font-size:14px}.path-card b{position:absolute;bottom:30px;font-size:15px}.path-card b i{display:inline-grid;place-items:center;width:27px;height:27px;margin-left:8px;border-radius:50%;background:var(--ink);color:#fff;font-style:normal}.principles{display:grid;grid-template-columns:repeat(3,1fr);max-width:1120px;margin:0 auto 90px;padding:0 28px;border-top:1px solid var(--line)}.principles article{padding:36px 34px 15px;border-right:1px solid var(--line)}.principles article:last-child{border:0}.principles b{color:var(--coral);font-size:12px;letter-spacing:.15em}.principles h3{margin:12px 0 8px;font-size:18px}.principles p{margin:0;color:#60726c;font-size:14px;line-height:1.8}
.page-shell{width:min(1080px,calc(100% - 48px));margin:0 auto;padding:66px 0 90px}.page-title{margin-bottom:38px}.page-title h1{margin:0;font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:clamp(36px,5vw,54px)}.page-title p{margin:12px 0 0;color:#60726c}.builder-panel{padding:30px;margin-bottom:38px;background:var(--paper);border:1px solid var(--line);border-radius:18px;box-shadow:0 9px 28px rgba(23,63,53,.06)}.selector-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:15px}.selector-grid label,.seed-field{display:grid;gap:8px}.selector-grid label span,.seed-field span,legend{font-size:13px;font-weight:800}select,.seed-field input{width:100%;height:50px;padding:0 14px;border:1px solid #bbbdb4;border-radius:9px;background:#fff;color:var(--ink)}select:disabled{opacity:1;color:var(--ink)}.builder-row{display:grid;grid-template-columns:1fr 1fr;gap:24px;margin-top:26px}fieldset{padding:0;border:0;margin:0}legend{margin-bottom:8px}.segmented{display:grid;grid-template-columns:repeat(3,1fr);height:50px;padding:4px;border-radius:9px;background:#ecece5}.segmented label{display:grid;place-items:center;border-radius:6px;cursor:pointer;font-weight:700}.segmented label.selected{background:#fff;box-shadow:0 2px 7px rgba(23,63,53,.12)}.segmented input,.count-pills input{position:absolute;opacity:0}.button-row{display:flex;flex-wrap:wrap;gap:12px;margin-top:28px}.button{display:inline-flex;min-height:48px;align-items:center;justify-content:center;padding:0 22px;border:2px solid transparent;border-radius:9px;text-decoration:none;font-weight:800;cursor:pointer}.button.primary{background:var(--coral);color:#fff}.button.secondary{border-color:var(--ink);background:transparent;color:var(--ink)}.button.dark{margin-left:auto;background:var(--ink);color:#fff}.button:disabled{cursor:not-allowed;opacity:.45}.helper{margin:15px 0 0;color:#687770;font-size:12px}
.worksheet{min-height:297mm;padding:17mm 18mm 13mm;background:#fff;color:#111;box-shadow:0 12px 35px rgba(23,63,53,.12)}.worksheet-header{display:flex;align-items:end;justify-content:space-between;padding-bottom:8mm;border-bottom:3px solid #111}.worksheet-header span{font-size:12px;font-weight:800}.worksheet-header h2{margin:2px 0 0;font-size:25px}.name-line{display:flex;align-items:end;gap:8px}.name-line span{width:55mm;border-bottom:1px solid #111}.worksheet-instruction{margin:9mm 0;font-weight:700}.problem-grid{display:grid;grid-template-columns:1fr 1fr;gap:10mm 16mm;margin:0;padding-left:9mm;font-size:20px}.problem-grid li{min-height:14mm;padding-left:3mm}.problem-grid li>.problem-prompt{display:inline-block;min-width:38mm;font-weight:600}.problem-grid li>i{display:inline-block;width:17mm;height:11mm;border-bottom:1px solid #222}.problem-grid.count-20{gap:6mm 14mm;font-size:17px}.problem-grid.count-20 li{min-height:10mm}.worksheet-footer{display:flex;justify-content:space-between;margin-top:14mm;padding-top:4mm;border-top:1px solid #aaa;color:#555;font-size:9px}.count-visual{display:inline-flex;align-items:center;gap:.16em;vertical-align:middle;white-space:nowrap}.count-dot{display:inline-block;width:.72em;height:.72em;border-radius:50%;background:currentColor}.answer-box{display:inline-block;width:.95em;height:.95em;margin:0 .1em;border:.11em solid currentColor;border-radius:.08em;vertical-align:-.08em}
.learn-page{max-width:820px}.learn-home-link{display:inline-block;margin-bottom:18px;color:#5f7069;font-size:13px;font-weight:800;text-decoration:none}.child-title{text-align:center}.learn-setup{padding:44px;border-radius:24px;background:var(--paper);border:1px solid var(--line);text-align:center;box-shadow:0 12px 35px rgba(23,63,53,.08)}.unit-chip{display:inline-flex;gap:7px;padding:7px 13px;border-radius:99px;background:#e5eee8;font-size:13px;font-weight:800}.unit-chip span{color:var(--coral)}.learn-setup h2{margin:22px 0 10px;font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:32px}.learn-setup>p{max-width:580px;margin:0 auto 32px;color:#61716c;line-height:1.8}.learn-setup legend{width:100%;margin-bottom:15px;font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:18px}.count-pills{display:flex;justify-content:center;gap:12px}.count-pills label{display:grid;place-content:center;width:86px;height:74px;border:2px solid var(--line);border-radius:15px;cursor:pointer;font-size:26px;font-weight:900}.count-pills label.selected{border-color:var(--coral);background:#fbe6df;color:var(--coral)}.count-pills small{font-size:10px}.big-start{min-width:230px;min-height:60px;margin:30px auto 0;border-radius:14px;background:var(--coral);color:#fff;font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:19px}.big-start span{margin-left:20px}.practice-page{min-height:100vh;padding:28px;background:var(--ink)}.practice-top{width:min(720px,100%);margin:0 auto;color:#fff}.text-button{padding:8px;border:0;background:transparent;color:inherit;cursor:pointer;font-weight:700}.progress-label{text-align:right;font-size:13px}.progress-label span{color:var(--yellow);font-size:22px;font-weight:900}.progress-track{height:10px;margin-top:8px;border-radius:99px;overflow:hidden;background:rgba(255,255,255,.16)}.progress-track span{display:block;height:100%;border-radius:inherit;background:var(--yellow);transition:width .3s}.problem-card{width:min(720px,100%);min-height:490px;margin:36px auto;padding:48px;display:flex;flex-direction:column;justify-content:center;border-radius:28px;background:var(--paper);text-align:center;box-shadow:0 16px 0 rgba(0,0,0,.15)}.question-label{color:var(--coral);font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-weight:900}.equation{display:flex;align-items:center;justify-content:center;gap:clamp(10px,3vw,26px);margin:54px 0 10px}.equation strong{font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:clamp(55px,11vw,92px)}.equation i{font-style:normal;font-size:clamp(30px,5vw,44px);font-weight:900}.equation input{width:clamp(95px,18vw,140px);height:clamp(95px,18vw,140px);border:4px solid var(--ink);border-radius:18px;background:#fff;color:var(--ink);text-align:center;font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:clamp(55px,10vw,80px);font-weight:900}.problem-card.correct .equation input{border-color:#198552;background:#e2f4e9}.problem-card.wrong .equation input{border-color:var(--coral)}.feedback-message{min-height:28px;margin:18px 0 0;font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:18px;font-weight:900}.correct-message{color:#147846}.wrong-message{color:#ba422a}.result-page{min-height:100vh;display:grid;place-items:center}.result-card{width:min(660px,100%);padding:50px;border-radius:25px;background:var(--paper);text-align:center}.celebration{width:90px;height:90px;display:grid;place-items:center;margin:0 auto 24px;border-radius:50%;background:var(--yellow);font-size:45px;transform:rotate(-5deg)}.result-card h1{font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif}.score{display:flex;align-items:center;justify-content:center;margin:30px 0}.score strong{color:var(--coral);font-size:84px;line-height:1}.score span{font-size:30px;font-weight:900}.score small{display:block;font-size:11px}.centered{justify-content:center}.history-page,.about-page{max-width:880px}.empty-state{padding:65px 30px;border:1px dashed #aeb4aa;border-radius:18px;text-align:center}.empty-state>span{font-size:44px}.empty-state h2{margin-bottom:6px}.empty-state p{margin-bottom:26px;color:#61716c}.history-toolbar{display:flex;justify-content:space-between;align-items:center;border-bottom:1px solid var(--line)}.danger{color:#b13624}.history-list{display:grid;gap:12px;padding:0;list-style:none}.history-list li{display:grid;grid-template-columns:80px 1fr auto;align-items:center;gap:18px;padding:18px;border:1px solid var(--line);border-radius:13px;background:var(--paper)}.history-score strong{color:var(--coral);font-size:28px}.history-score span{font-weight:800}.history-list li>div:nth-child(2){display:grid}.history-list li>div:nth-child(2) span,.history-list time{color:#697871;font-size:12px}.source-card{padding:38px;border:1px solid var(--line);border-radius:18px;background:var(--paper)}.source-card h2{font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:30px}.source-card>p,.source-card li{line-height:1.8}.source-card h3{margin-top:30px;padding-top:20px;border-top:1px solid var(--line);font-size:16px}.source-location{padding:18px;background:#f1f0e8;border-radius:9px;font-size:13px}.reference-list{display:grid;gap:12px;padding:0;list-style:none}.reference-list li{display:grid}.reference-list a{display:flex;align-items:center;gap:8px;font-weight:700}.reference-list a span{padding:2px 6px;border-radius:4px;background:#e5eee8;color:var(--ink);font-size:10px}.reference-list a i{font-style:normal}.reference-list small{color:#718079}.notice{padding:15px;border-left:4px solid var(--yellow);background:#fff8d9;font-size:12px}.site-footer{display:flex;justify-content:space-between;align-items:center;min-height:120px;padding:30px max(28px,calc((100vw - 1120px)/2));background:var(--ink);color:#d7e3dc;font-size:12px}.site-footer a{font-weight:700}
@media(max-width:760px){.site-header{height:auto;padding:14px 18px;align-items:flex-start}.brand{font-size:16px}nav{gap:0}nav a{padding:10px 8px;font-size:11px}.hero{grid-template-columns:1fr;gap:25px;padding:55px 25px}.hero-visual{min-height:210px;transform:scale(.72);margin:-20px -90px}.path-grid,.principles,.selector-grid,.builder-row{grid-template-columns:1fr}.principles article{border-right:0;border-bottom:1px solid var(--line)}.page-shell{width:min(100% - 28px,1080px);padding-top:42px}.builder-panel,.learn-setup,.problem-card,.source-card{padding:25px 18px}.button-row .button{flex:1 1 100%}.button.dark{margin-left:0}.worksheet{padding:10mm 7mm}.worksheet-header{align-items:flex-start;gap:10px}.name-line span{width:28mm}.problem-grid{gap:7mm 8mm;font-size:16px}.problem-grid li span{min-width:28mm}.practice-page{padding:18px 12px}.problem-card{min-height:420px;margin-top:24px}.history-list li{grid-template-columns:60px 1fr}.history-list time{grid-column:2}.site-footer{display:grid;gap:12px}}@media print{@page{size:A4 portrait;margin:0}html,body,#root,.app{margin:0;padding:0;background:#fff}.no-print,.offline-banner{display:none!important}.print-page{width:auto;margin:0;padding:0}.worksheet{width:210mm;min-height:297mm;margin:0;padding:17mm 18mm 13mm;box-shadow:none;break-after:avoid}.problem-grid{break-inside:avoid}}@media(prefers-reduced-motion:reduce){*,*:before,*:after{scroll-behavior:auto!important;transition:none!important}}

/* Home: two clear starting points for print and web practice. */
.home-intro{display:grid;grid-template-columns:minmax(0,1.1fr) minmax(300px,.9fr);align-items:center;gap:76px;min-height:490px;padding:76px max(28px,calc((100vw - 1120px)/2));overflow:hidden;background:var(--ink);color:#fff}.home-intro .eyebrow{color:var(--yellow)}.home-intro h1{margin:0;font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:clamp(48px,6.4vw,78px);line-height:1.16;letter-spacing:-.04em}.home-intro h1 em{color:var(--yellow);font-style:normal}.home-intro p{max-width:560px;margin:25px 0 0;color:#d9e6df;font-size:16px;line-height:1.95;font-weight:600}.home-equation{display:flex;align-items:center;justify-content:center;gap:clamp(7px,1.5vw,18px);min-height:270px;font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-weight:900}.home-equation span{display:grid;place-items:center;width:clamp(66px,9vw,108px);aspect-ratio:1;border-radius:24px;background:var(--paper);color:var(--ink);box-shadow:0 12px 0 rgba(0,0,0,.16);font-size:clamp(42px,6vw,70px)}.home-equation span:first-child{transform:rotate(-7deg)}.home-equation span:nth-of-type(2){transform:rotate(6deg);background:#e9cfc3}.home-equation b{font-size:clamp(28px,3.5vw,42px)}.home-equation strong{display:grid;place-items:center;width:clamp(76px,10vw,124px);aspect-ratio:1;border-radius:50%;background:var(--yellow);color:var(--ink);font-size:clamp(48px,7vw,76px);transform:rotate(-5deg)}.learning-paths{width:min(1120px,calc(100% - 56px));margin:0 auto;padding:84px 0 46px}.home-section-heading{margin-bottom:34px}.home-section-heading span{color:var(--coral);font-size:11px;font-weight:900;letter-spacing:.19em}.home-section-heading h2{margin:9px 0 0;font-family:ui-rounded,'Hiragino Maru Gothic ProN',sans-serif;font-size:clamp(30px,4vw,42px)}.home .path-grid{gap:24px}.home .path-card{min-height:350px;padding:38px;border:1px solid transparent;border-radius:24px}.home .path-card:hover{border-color:var(--ink)}.home .path-card small{margin:0 0 11px;color:#60726c;font-weight:800}.home .path-card strong{font-size:clamp(27px,3vw,35px)}.home .path-card>span:not(.path-icon):not(.path-number){margin-top:10px;line-height:1.7}.home .path-card b{bottom:32px}.home-note{width:min(1120px,calc(100% - 56px));margin:0 auto 86px;padding:21px 0;border-top:1px solid var(--line);display:flex;align-items:center;gap:20px;color:#60726c;font-weight:700}.home-note span{color:var(--coral);font-size:11px;font-weight:900;letter-spacing:.14em}.home-note p{margin:0;font-size:14px}@media(max-width:760px){.home-intro{grid-template-columns:1fr;gap:18px;min-height:0;padding:54px 25px 36px}.home-intro h1{font-size:clamp(43px,13vw,61px)}.home-intro p{font-size:14px}.home-equation{min-height:170px;transform:scale(.82);margin:-8px -32px}.learning-paths{width:min(100% - 36px,1120px);padding:52px 0 32px}.home .path-grid{grid-template-columns:1fr}.home .path-card{min-height:300px;padding:29px 25px}.home-note{width:min(100% - 36px,1120px);align-items:flex-start;flex-direction:column;gap:7px;margin-bottom:55px}.home-note p{font-size:13px}}